U.S. official: Almost no doubt Assad regime used chemical weapons

Frederik Pleitgen, Hamdi Alkhshali and Josh Levs, CNN
Updated 10:35 PM EDT, Sun August 25, 2013
In this photo provided by the anti-government activist group Aleppo Media Center, Syrian men help survivors out of a building in Aleppo after it was bombed, allegedly by a Syrian regime warplane on Saturday, February 8. The United Nations estimates more than 100,000 people have been killed since the Syrian conflict began in March 2011. Click through to see the most compelling images taken during the conflict, which is now a civil war:
Syrian civil war in photos —
In this photo provided by the anti-government activist group Aleppo Media Center, Syrian men help survivors out of a building in Aleppo after it was bombed, allegedly by a Syrian regime warplane on Saturday, February 8. The United Nations estimates more than 100,000 people have been killed since the Syrian conflict began in March 2011. Click through to see the most compelling images taken during the conflict, which is now a civil war:
Aleppo Media Center AMC/AP
Syrians gather at a site hit by barrel bombs, allegedly dropped by a regime helicopter on the opposition-controlled Mesekin Hananu district of Aleppo on February 8.
Syrian civil war in photos —
Syrians gather at a site hit by barrel bombs, allegedly dropped by a regime helicopter on the opposition-controlled Mesekin Hananu district of Aleppo on February 8.
Mustafa Sultan/Anadolu Agency/Getty Images
Civilians wave national flags as they take part in a rally in support of Syrian President Bashar al-Assad in Damascus, in a handout photo released by the official Syrian Arab News Agency on February 8.
Syrian civil war in photos —
Civilians wave national flags as they take part in a rally in support of Syrian President Bashar al-Assad in Damascus, in a handout photo released by the official Syrian Arab News Agency on February 8.
AFP/Getty Images
A man stands next to debris in the road following a reported airstrike by Syrian government forces in the northern city of Aleppo on February 8.
Syrian civil war in photos —
A man stands next to debris in the road following a reported airstrike by Syrian government forces in the northern city of Aleppo on February 8.
MOHAMMED WESAM/AFP/Getty Images
Medical personnel look for survivors after a reported airstrike in Aleppo, Syria, on Saturday, February 1.
Syrian civil war in photos —
Medical personnel look for survivors after a reported airstrike in Aleppo, Syria, on Saturday, February 1.
MOHAMMED AL-KHATIEB/AFP/Getty Images
Syrians carry a dead body following an airstrike on February 1.
Syrian civil war in photos —
Syrians carry a dead body following an airstrike on February 1.
ZEIN AL-RIFAI/AFP/Getty Images
A man walks amid debris and dust on January 31.
Syrian civil war in photos —
A man walks amid debris and dust on January 31.
AFP PHOTO/MOHAMMED AL-KHATIEB/getty images
An injured man is covered in dust after an airstrike on January 29.
Syrian civil war in photos —
An injured man is covered in dust after an airstrike on January 29.
MOHAMMED AL-KHATIEB/AFP/Getty Images
A man tries to fix electrical wires in a neighborhood of Aleppo, Syria, on January 27.
Syrian civil war in photos —
A man tries to fix electrical wires in a neighborhood of Aleppo, Syria, on January 27.
STRinger/AFP/Getty Images
Rebels and civilians check out a crater that activists say resulted from a Syrian government airstrike on an Aleppo bus station on Tuesday, January 21.
Syrian civil war in photos —
Rebels and civilians check out a crater that activists say resulted from a Syrian government airstrike on an Aleppo bus station on Tuesday, January 21.
AMMAR ABDULLAH/REUTERS/LANDOV
Men rush to a site that Syrian government forces reportedly hit in Aleppo on January 21.
Syrian civil war in photos —
Men rush to a site that Syrian government forces reportedly hit in Aleppo on January 21.
STRINGER/reuters/LANDOV
Buildings lie in ruins in Aleppo on Sunday, January 19, after reported air raids by Syrian government planes.
Syrian civil war in photos —
Buildings lie in ruins in Aleppo on Sunday, January 19, after reported air raids by Syrian government planes.
MOHAMMED WESAM/AFP/Getty Images
A Syrian child collects items from a garbage pile on Saturday, January 18, in Douma, northeast of the capital.
Syrian civil war in photos —
A Syrian child collects items from a garbage pile on Saturday, January 18, in Douma, northeast of the capital.
MAJD ALDEEK/AFP/Getty Images
A piece of exploded mortar lies in a street in Daraya, a city southwest of Damascus, on Friday, January 17.
Syrian civil war in photos —
A piece of exploded mortar lies in a street in Daraya, a city southwest of Damascus, on Friday, January 17.
FADI DIRANI/AFP/Getty Images
Residents search for survivors in Aleppo on Saturday, December 28, 2013, after what activists said were airstrikes by forces loyal to Syrian President Bashar al-Assad.
Syrian civil war in photos —
Residents search for survivors in Aleppo on Saturday, December 28, 2013, after what activists said were airstrikes by forces loyal to Syrian President Bashar al-Assad.
STRINGER/reuters/LANDOV
A man appears distraught after an air raid in Aleppo on Monday, December 23.
Syrian civil war in photos —
A man appears distraught after an air raid in Aleppo on Monday, December 23.
Saad Abobrahim/Reuters/Landov
Free Syrian Army fighters sit in a damaged house in Old Aleppo on Saturday, December 21.
Syrian civil war in photos —
Free Syrian Army fighters sit in a damaged house in Old Aleppo on Saturday, December 21.
Abdalrhman Ismail/Reuters/Stringer/Landov
People search for survivors amid the rubble after an airstrike in Aleppo on Tuesday, December 17.
Syrian civil war in photos —
People search for survivors amid the rubble after an airstrike in Aleppo on Tuesday, December 17.
MOHAMMED AL-KHATIEB/AFP/Getty Images
A man sits on the ground after the airstrike in Aleppo on December 17.
Syrian civil war in photos —
A man sits on the ground after the airstrike in Aleppo on December 17.
MOHAMMED AL-KHATIEB/AFP/Getty Images
A woman carries children following airstrikes on a rebel area of Aleppo on Sunday, December 15.
Syrian civil war in photos —
A woman carries children following airstrikes on a rebel area of Aleppo on Sunday, December 15.
MOHAMMED AL-KHATIEB/AFP/Getty Images
Syrians look at the aftermath of an airstrike on a rebel area of Aleppo on December 15.
Syrian civil war in photos —
Syrians look at the aftermath of an airstrike on a rebel area of Aleppo on December 15.
MOHAMMED AL-KHATIEB/AFP/Getty Images
Syrians help a wounded woman following airstrikes in Aleppo on December 15.
Syrian civil war in photos —
Syrians help a wounded woman following airstrikes in Aleppo on December 15.
MOHAMMED AL-KHATIEB/AFP/Getty Images
Syrians look at the aftermath of an airstrike on a rebel area of Aleppo on December 15.
Syrian civil war in photos —
Syrians look at the aftermath of an airstrike on a rebel area of Aleppo on December 15.
MOHAMMED AL-KHATIEB/AFP/Getty Images
Syrian rebel fighters clash with pro-government forces in Aleppo on Wednesday, December 11.
Syrian civil war in photos —
Syrian rebel fighters clash with pro-government forces in Aleppo on Wednesday, December 11.
MEDO HALAB/AFP/Getty Images
A woman weeps inside a damaged vehicle after forces loyal to President Bashar al-Assad captured the town of Nabak on Monday, December 9.
Syrian civil war in photos —
A woman weeps inside a damaged vehicle after forces loyal to President Bashar al-Assad captured the town of Nabak on Monday, December 9.
STRinger/AFP/Getty Images
A rebel fighter takes position during fighting with government forces in Deir Ezzor on Monday, December 2.
Syrian civil war in photos —
A rebel fighter takes position during fighting with government forces in Deir Ezzor on Monday, December 2.
AHMAD ABOUD/AFP/Getty Images
Shiite fighters from a group called the Hussein Brigade search for rebels from the Free Syrian Army in Hejeira on Thursday, November 21.
Syrian civil war in photos —
Shiite fighters from a group called the Hussein Brigade search for rebels from the Free Syrian Army in Hejeira on Thursday, November 21.
Jaber al-Helo/AP
Free Syrian Army rebels battle government forces in Aleppo on Monday, November 18.
Syrian civil war in photos —
Free Syrian Army rebels battle government forces in Aleppo on Monday, November 18.
KARAM AL-MASRI/AFP/Getty Images
A rebel fighter holds his position in a damaged building during clashes with government forces in Deir Ezzor on Monday, November 11.
Syrian civil war in photos —
A rebel fighter holds his position in a damaged building during clashes with government forces in Deir Ezzor on Monday, November 11.
AHMAD ABOUD/AFP/Getty Images
A rebel fighter fires during clashes with government forces in Deir Ezzor on November 11.
Syrian civil war in photos —
A rebel fighter fires during clashes with government forces in Deir Ezzor on November 11.
AHMAD ABOUD/AFP/Getty Images
A rebel fighter prepares an improvised mortar shell in Aleppo, Syria, on Saturday, November 9.
Syrian civil war in photos —
A rebel fighter prepares an improvised mortar shell in Aleppo, Syria, on Saturday, November 9.
FOUAD HALLAK/AFP/Getty Images
Two injured men are transported on a cart in Aleppo, Syria, following shelling as fighting between pro-government forces and rebels continues on Saturday, October 26.
Syrian civil war in photos —
Two injured men are transported on a cart in Aleppo, Syria, following shelling as fighting between pro-government forces and rebels continues on Saturday, October 26.
KARAM AL-MASRI/AFP/Getty Images
Rebel fighters hold a position in Deir Ezzor, Syria, on Thursday, October 24.
Syrian civil war in photos —
Rebel fighters hold a position in Deir Ezzor, Syria, on Thursday, October 24.
Ahmad Aboud/AFP/Getty Images
An opposition fighter stands in the doorway of a building as he smokes a cigarette in Deir Ezzor, Syria, on Tuesday, October 22.
Syrian civil war in photos —
An opposition fighter stands in the doorway of a building as he smokes a cigarette in Deir Ezzor, Syria, on Tuesday, October 22.
Ahmad Aboud/AFP/Getty Images
People use buckets as they try to extinguish a fire that ignited at a fuel station in Aleppo, Syria, on Sunday, October 20.
Syrian civil war in photos —
People use buckets as they try to extinguish a fire that ignited at a fuel station in Aleppo, Syria, on Sunday, October 20.
KARAM AL-MASRI/AFP/Getty Images
A Syrian opposition fighter aims a catapult toward regime forces in Aleppo, Syria, on Thursday, October 17.
Syrian civil war in photos —
A Syrian opposition fighter aims a catapult toward regime forces in Aleppo, Syria, on Thursday, October 17.
KARAM AL-MASRI/AFP/Getty Images
Firefighters extinguish a burning vehicle after two mortar rounds struck the Abu Roumaneh area in Damascus, Syria, on Saturday, October 12.
Syrian civil war in photos —
Firefighters extinguish a burning vehicle after two mortar rounds struck the Abu Roumaneh area in Damascus, Syria, on Saturday, October 12.
ap
An opposition fighter aims as others run for cover while they hold a position behind burning tires in the Salaheddin district of the northern Syrian city of Aleppo on Wednesday, October 9.
Syrian civil war in photos —
An opposition fighter aims as others run for cover while they hold a position behind burning tires in the Salaheddin district of the northern Syrian city of Aleppo on Wednesday, October 9.
TAREK ABU Al-FAHEM/AFP/Getty Images
An opposition fighter smokes a cigarette as he takes a break following the injury of his friend in the Salaheddin neighborhood of Aleppo on October 9.
Syrian civil war in photos —
An opposition fighter smokes a cigarette as he takes a break following the injury of his friend in the Salaheddin neighborhood of Aleppo on October 9.
KARAM AL-MASRI/AFP/Getty Images
Smoke rises after a mortar shell hit a residential area during fighting between Syrian government forces and rebels in Maaret al-Numan, Syria, on October, 9.
Syrian civil war in photos —
Smoke rises after a mortar shell hit a residential area during fighting between Syrian government forces and rebels in Maaret al-Numan, Syria, on October, 9.
AP
Rebel fighters cover a car in mud for camouflage at an undisclosed location in Syria's northwestern province of Idlib on Tuesday, October 8.
Syrian civil war in photos —
Rebel fighters cover a car in mud for camouflage at an undisclosed location in Syria's northwestern province of Idlib on Tuesday, October 8.
MOHAMAD JADAAN/AFP/Getty Images
Masked female rebel fighters walk alongside their trainer on a street in the Salaheddin district of Aleppo, Syria, on October 8.
Syrian civil war in photos —
Masked female rebel fighters walk alongside their trainer on a street in the Salaheddin district of Aleppo, Syria, on October 8.
KARAM AL-MASRI/AFP/Getty Images
A rebel fighter prays moments before heading into battle in Maaret al-Numan, Syria, on Monday, October 7.
Syrian civil war in photos —
A rebel fighter prays moments before heading into battle in Maaret al-Numan, Syria, on Monday, October 7.
AP
A mother comforts her baby in an area where she and her family have taken shelter after fleeing their village turned battlefield in Syria's Idlib province on Sunday, September 22.
Syrian civil war in photos —
A mother comforts her baby in an area where she and her family have taken shelter after fleeing their village turned battlefield in Syria's Idlib province on Sunday, September 22.
Stringer/AP
A man checks an AK-47 at his gun shop in Aleppo, Syria, on Saturday, September 21.
Syrian civil war in photos —
A man checks an AK-47 at his gun shop in Aleppo, Syria, on Saturday, September 21.
JM LOPEZ/AFP/Getty Images
Free Syrian Army fighters take cover moments after firing a rocket toward government forces in the Idlib province of northern Syria on Friday, September 20.
Syrian civil war in photos —
Free Syrian Army fighters take cover moments after firing a rocket toward government forces in the Idlib province of northern Syria on Friday, September 20.
AP
Rebel fighters inspect a stairwell amid fighting against Syrian government forces on Thursday, September 19, in the Saif al-Dawla district of Aleppo, Syria.
Syrian civil war in photos —
Rebel fighters inspect a stairwell amid fighting against Syrian government forces on Thursday, September 19, in the Saif al-Dawla district of Aleppo, Syria.
JM LOPEZ/AFP/Getty Images
A Syrian child sits in a village in the Idlib province countryside on September 19.
Syrian civil war in photos —
A Syrian child sits in a village in the Idlib province countryside on September 19.
AP
Opposition fighters react after returning from the battlefield in the Idlib province countryside on September 19.
Syrian civil war in photos —
Opposition fighters react after returning from the battlefield in the Idlib province countryside on September 19.
ap
Smoke rises after a bomb was thrown from a helicopter, hitting a rebel position during heavy fighting between troops loyal to Syrian President Bashar al-Assad and opposition fighters in the Idlib province on September 19.
Syrian civil war in photos —
Smoke rises after a bomb was thrown from a helicopter, hitting a rebel position during heavy fighting between troops loyal to Syrian President Bashar al-Assad and opposition fighters in the Idlib province on September 19.
ap
Rebel fighters duck behind a barricade from firing in Aleppo on Wednesday, September 18.
Syrian civil war in photos —
Rebel fighters duck behind a barricade from firing in Aleppo on Wednesday, September 18.
JM LOPEZ/AFP/Getty Images
AFP reporter Sammy Ketz hits the ground as a Syrian soldier runs past during sniper fire in Maalula on September 18. Ketz and a photographer were reporting on the ancient Christian Syrian town northeast of Damascus.
Syrian civil war in photos —
AFP reporter Sammy Ketz hits the ground as a Syrian soldier runs past during sniper fire in Maalula on September 18. Ketz and a photographer were reporting on the ancient Christian Syrian town northeast of Damascus.
ANWAR AMRO/AFP/Getty Images
A Syrian opposition fighter takes a break on a mountain near a rebel camp in Idlib province on September 18.
Syrian civil war in photos —
A Syrian opposition fighter takes a break on a mountain near a rebel camp in Idlib province on September 18.
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A Free Syrian Army fighter rests inside a cave at a rebel camp in Idlib province on Tuesday, September 17.
Syrian civil war in photos —
A Free Syrian Army fighter rests inside a cave at a rebel camp in Idlib province on Tuesday, September 17.
Narciso Contreras/AP
Volunteers wear protective gear to show a class how to respond to a chemical attack in Aleppo, Syria, on September 15. For two months, Mohammad Zayed, an Aleppo University student, has been training a group of 26 civilians to respond to a chemical attack.
Syrian civil war in photos —
Volunteers wear protective gear to show a class how to respond to a chemical attack in Aleppo, Syria, on September 15. For two months, Mohammad Zayed, an Aleppo University student, has been training a group of 26 civilians to respond to a chemical attack.
JM LOPEZ/AFP/Getty Images
Syria's pro-Assad militia rest near Maalula, Syria, on Friday, September 13.
Syrian civil war in photos —
Syria's pro-Assad militia rest near Maalula, Syria, on Friday, September 13.
POCHUYEV MIKHAIL/ITAR-TASS /Landov
Syrian soldiers take aim at rebel fighters positioned in the mountains of the Christian town of Maalula on September 13.
Syrian civil war in photos —
Syrian soldiers take aim at rebel fighters positioned in the mountains of the Christian town of Maalula on September 13.
Stringer/AFP/Getty Images
Rebels parade at a former military academy north of Aleppo during a September 13 ceremony to mark an agreement to unite two rebel brigade forces.
Syrian civil war in photos —
Rebels parade at a former military academy north of Aleppo during a September 13 ceremony to mark an agreement to unite two rebel brigade forces.
JM LOPEZ/AFP/Getty Images
A fighter of the Popular Front for the Liberation of Palestine General Command squats next to the covered body of an alleged foreign rebel fighter in the Yarmouk refugee camp in the Syrian capital of Damascus on Thursday, September 12.
Syrian civil war in photos —
A fighter of the Popular Front for the Liberation of Palestine General Command squats next to the covered body of an alleged foreign rebel fighter in the Yarmouk refugee camp in the Syrian capital of Damascus on Thursday, September 12.
ANWAR AMRO/AFP/Getty Images
An opposition fighter runs in front of a sniper curtain in the industrial area of Deir Ezzor, Syria, during clashes with regime forces on September 12.
Syrian civil war in photos —
An opposition fighter runs in front of a sniper curtain in the industrial area of Deir Ezzor, Syria, during clashes with regime forces on September 12.
ABO SHUJA/AFP/Getty Images
A sheet hangs across an alley way to shield fighters from sniper fire as a fighter of the Popular Front for the Liberation of Palestine General Command walks past destroyed buildings in the Yarmouk refugee camp in Damascus, Syria, on September 12.
Syrian civil war in photos —
A sheet hangs across an alley way to shield fighters from sniper fire as a fighter of the Popular Front for the Liberation of Palestine General Command walks past destroyed buildings in the Yarmouk refugee camp in Damascus, Syria, on September 12.
ANWAR AMRO/AFP/Getty Images
A Free Syrian Army fighter stands guard inside a damaged house in Aleppo's Qastal al-Harami neighborhood on September 11.
Syrian civil war in photos —
A Free Syrian Army fighter stands guard inside a damaged house in Aleppo's Qastal al-Harami neighborhood on September 11.
Nour Kelze/Reuters/Stringer/Landov
Free Syrian Army fighters climb a flight of stairs to take positions near the Hanano barracks on September 11.
Syrian civil war in photos —
Free Syrian Army fighters climb a flight of stairs to take positions near the Hanano barracks on September 11.
Muzaffar Salman/Reuters/Landov
A Syrian government tank is seen during clashes with Free Syrian Army fighters in Maaloula, Syria, on September 11.
Syrian civil war in photos —
A Syrian government tank is seen during clashes with Free Syrian Army fighters in Maaloula, Syria, on September 11.
SANA/ap
A funeral is held on September 11 for three Christian Syrians killed during battles with an al Qaeda-linked rebel group that took control of the historic Christian town of Maaloula from regime forces during the weekend.
Syrian civil war in photos —
A funeral is held on September 11 for three Christian Syrians killed during battles with an al Qaeda-linked rebel group that took control of the historic Christian town of Maaloula from regime forces during the weekend.
ANWAR AMRO/AFP/Getty Images
A man walks through a destroyed residential area of Saraqib, Syria, on Monday, September 9, following repeated airstrikes by government forces.
Syrian civil war in photos —
A man walks through a destroyed residential area of Saraqib, Syria, on Monday, September 9, following repeated airstrikes by government forces.
GIOVANNI DIFFIDENTI/AFP/Getty Images
A soldier wears a picture of Syrian President Bashar al-Assad on his chest while at a market in old Damascus on September 8.
Syrian civil war in photos —
A soldier wears a picture of Syrian President Bashar al-Assad on his chest while at a market in old Damascus on September 8.
KHALED AL-HARIRI/REUTERS/LANDOV
A Free Syrian Army fighter prays in a trench in the Damascus suburbs on September 8.
Syrian civil war in photos —
A Free Syrian Army fighter prays in a trench in the Damascus suburbs on September 8.
Raje Alsori/REUTERS/LANDOV
A Free Syrian Army fighter takes up a shooting position in Aleppo on September 8.
Syrian civil war in photos —
A Free Syrian Army fighter takes up a shooting position in Aleppo on September 8.
Hamid Khatib/REUTERS/LANDOV
A Free Syrian Army fighter runs for cover in Raqqa province on September 8.
Syrian civil war in photos —
A Free Syrian Army fighter runs for cover in Raqqa province on September 8.
Nour Fourat/REUTERS/LANDOV
Buildings are heavily damaged in the Salah al-Din area of Aleppo on September 8.
Syrian civil war in photos —
Buildings are heavily damaged in the Salah al-Din area of Aleppo on September 8.
ABO MHIO/AFP/Getty Images
<a href="http://www.cnn.com/2013/09/09/world/gallery/issa-syria/index.html" target="_blank">A boy named Issa</a>, 10, carries a mortar shell in a weapons factory of the Free Syrian Army in Aleppo on Saturday, September 7. The boy works with his father in the factory.
Syrian civil war in photos —
A boy named Issa, 10, carries a mortar shell in a weapons factory of the Free Syrian Army in Aleppo on Saturday, September 7. The boy works with his father in the factory.
Hamid Khatib/reuters/landov
Issa fixes a mortar launcher in the Aleppo weapons factory on September 7.
Syrian civil war in photos —
Issa fixes a mortar launcher in the Aleppo weapons factory on September 7.
Hamid Khatib/reuters/landov
A bedroom lies in ruins after clashes between government forces and rebels around Ariha on September 7.
Syrian civil war in photos —
A bedroom lies in ruins after clashes between government forces and rebels around Ariha on September 7.
Houssam Abo Dabak/REUTERS/LANDOV
Syrian forces are seen in the Syrian Christian town of Maaloula on September 7.
Syrian civil war in photos —
Syrian forces are seen in the Syrian Christian town of Maaloula on September 7.
stringer/AFP/Getty images
A Syrian soldier prepares large-caliber bullets for a machine gun in Maaloula on September 7.
Syrian civil war in photos —
A Syrian soldier prepares large-caliber bullets for a machine gun in Maaloula on September 7.
stringer/AFP/Getty images
A man stands inside a home damaged by heavy shelling in Arbeen, a suburb of Damascus, Syria, on September 7.
Syrian civil war in photos —
A man stands inside a home damaged by heavy shelling in Arbeen, a suburb of Damascus, Syria, on September 7.
Local Comity of Arbeen/ap
Men gather on the remains of a destroyed building after reported airstrikes by Syrian government forces in the rebel-held northwestern Syrian province of Idlib on Thursday, September 5.
Syrian civil war in photos —
Men gather on the remains of a destroyed building after reported airstrikes by Syrian government forces in the rebel-held northwestern Syrian province of Idlib on Thursday, September 5.
ABU AMAR AL-TAFTANAZ/AFP/Getty Image
A Free Syrian Army fighter takes cover as he watches forces loyal to President Bashar al-Assad near Hanano barracks in Aleppo on September 3.
Syrian civil war in photos —
A Free Syrian Army fighter takes cover as he watches forces loyal to President Bashar al-Assad near Hanano barracks in Aleppo on September 3.
Hamid Khatib/Reuters/Stringer/Landov
Free Syrian Army fighters walk inside a damaged house in Aleppo on September 3.
Syrian civil war in photos —
Free Syrian Army fighters walk inside a damaged house in Aleppo on September 3.
Hamid Khatib/Reuters/Stringer/Landov
Free Syrian Army fighters talk inside a burnt house in Aleppo on September 3.
Syrian civil war in photos —
Free Syrian Army fighters talk inside a burnt house in Aleppo on September 3.
Hamid Khatib/Reuters/Stringer/Landov
A Free Syrian Army fighter peeks through the curtains of a bedroom in Deir ez-Zor, Syria, on Monday, September 2.
Syrian civil war in photos —
A Free Syrian Army fighter peeks through the curtains of a bedroom in Deir ez-Zor, Syria, on Monday, September 2.
Khalil Ashawi/Reuters/Stringer/Landov
Free Syrian Army fighters take their positions behind piled sandbags, as one of them points his weapon, in Deir ez-Zor on September 2.
Syrian civil war in photos —
Free Syrian Army fighters take their positions behind piled sandbags, as one of them points his weapon, in Deir ez-Zor on September 2.
Khalil Ashawi/Reuters/Stringer/Landov
A rebel fighter points his weapon at Syrian regime forces in Deir ez-Zor on September 2.
Syrian civil war in photos —
A rebel fighter points his weapon at Syrian regime forces in Deir ez-Zor on September 2.
ABO SHUJA/AFP/Getty Images
Syrian firefighters try to extinguish a fire after a missile hit a residential building in Damascus, Syria, on September 2.
Syrian civil war in photos —
Syrian firefighters try to extinguish a fire after a missile hit a residential building in Damascus, Syria, on September 2.
SANA/AP
A U.N. arms expert collects samples during an inspection of a suspected chemical weapons strike site in the Ghouta area outside Damascus on August 29.
Syrian civil war in photos —
A U.N. arms expert collects samples during an inspection of a suspected chemical weapons strike site in the Ghouta area outside Damascus on August 29.
Ammar al-Arbini/AFP/Getty Images
People search for belongings in rubble in Raqqa, Syria, on August 29.
Syrian civil war in photos —
People search for belongings in rubble in Raqqa, Syria, on August 29.
STRINGER/Reuters/LANDOV
Free Syrian Army fighters launch a rocket toward forces loyal to Syrian President Bashar al-Assad in Deir Ezzor on August 29.
Syrian civil war in photos —
Free Syrian Army fighters launch a rocket toward forces loyal to Syrian President Bashar al-Assad in Deir Ezzor on August 29.
Khalil Ashawi/reuters/landov
A Syrian Kurd uses hay to hide another woman in a training session organized by the Kurdish Women's Defense Units on Wednesday, August 28, in a northern Syrian border village. They're preparing if the area comes under attack.
Syrian civil war in photos —
A Syrian Kurd uses hay to hide another woman in a training session organized by the Kurdish Women's Defense Units on Wednesday, August 28, in a northern Syrian border village. They're preparing if the area comes under attack.
BENJAMIN HILLER/AFP/Getty Images
Free Syrian Army fighters escort U.N. vehicles with chemical weapons experts on August 28 through a site of a suspected chemical weapons attack outside Damascus.
Syrian civil war in photos —
Free Syrian Army fighters escort U.N. vehicles with chemical weapons experts on August 28 through a site of a suspected chemical weapons attack outside Damascus.
Bassam Khabieh/REUTERS/landov
A Free Syrian Army fighter takes position behind sandbags in the old city of Aleppo, Syria, on Tuesday, August 27.
Syrian civil war in photos —
A Free Syrian Army fighter takes position behind sandbags in the old city of Aleppo, Syria, on Tuesday, August 27.
Stringer/reuters/landov
A U.N. team leaves its Damascus, Syria, hotel in a convoy on Monday, August 26. The team was to investigate an alleged chemical attack that killed hundreds last week in a suburb of the Syrian capital. Sniper fire hit a vehicle used by the U.N. chemical weapons investigation team multiple times Monday, according to the United Nations.
Syrian civil war in photos —
A U.N. team leaves its Damascus, Syria, hotel in a convoy on Monday, August 26. The team was to investigate an alleged chemical attack that killed hundreds last week in a suburb of the Syrian capital. Sniper fire hit a vehicle used by the U.N. chemical weapons investigation team multiple times Monday, according to the United Nations.
Stringer/AP
A Syrian soldier walks down a street in Damascus on Saturday, August 24.
Syrian civil war in photos —
A Syrian soldier walks down a street in Damascus on Saturday, August 24.
stringer/AP
Pigeons lie dead on the ground on August 24 from after what activists say is the use of chemical weapons by government forces in the Damascus suburb of Arbeen.
Syrian civil war in photos —
Pigeons lie dead on the ground on August 24 from after what activists say is the use of chemical weapons by government forces in the Damascus suburb of Arbeen.
STRINGER/reuters/LANDOV
Columns of smoke rise in Barzeh after heavy shelling on Friday, August 23.
Syrian civil war in photos —
Columns of smoke rise in Barzeh after heavy shelling on Friday, August 23.
Hassan Ammar/AP
A young Free Syrian Army fighter is reflected in a mirror as he takes position in a house in Aleppo on Thursday, August 22.
Syrian civil war in photos —
A young Free Syrian Army fighter is reflected in a mirror as he takes position in a house in Aleppo on Thursday, August 22.
MUZAFFAR SALMAN/reuters/LANDOV
Rebels move around a building in Aleppo on August 22.
Syrian civil war in photos —
Rebels move around a building in Aleppo on August 22.
MUZAFFAR SALMAN/reuters/LANDOV
Syrian rebels claim pro-government forces used chemical weapons to kill citizens outside Damascus on Wednesday, August 21. People inspect bodies in this photo released by the Syrian opposition Shaam News Network.
Syrian civil war in photos —
Syrian rebels claim pro-government forces used chemical weapons to kill citizens outside Damascus on Wednesday, August 21. People inspect bodies in this photo released by the Syrian opposition Shaam News Network.
SHAAM NEWS NETWORK/AFP/Getty Images
People search the rubble of a bombed building in Aleppo, Syria, on Friday, August 16.
Syrian civil war in photos —
People search the rubble of a bombed building in Aleppo, Syria, on Friday, August 16.
FOUAD/AFP/Getty Images
Men bury the bodies of six members of the same family killed in a bombing in Raqqa on Saturday, August 10.
Syrian civil war in photos —
Men bury the bodies of six members of the same family killed in a bombing in Raqqa on Saturday, August 10.
ALICE Martins/AFP/Getty Images
Syrian Army soldiers patrol a devastated street in Homs on Wednesday, July 31.
Syrian civil war in photos —
Syrian Army soldiers patrol a devastated street in Homs on Wednesday, July 31.
JOSEPH EID/AFP/Getty Images
Free Syrian Army fighters move through a hole in a wall in Khan al-Assal on Monday, July 22, after seizing the town.
Syrian civil war in photos —
Free Syrian Army fighters move through a hole in a wall in Khan al-Assal on Monday, July 22, after seizing the town.
Hamid Khatib/reuters/LANDOv
A rebel fighter walks past swings in a deserted playground in Deir al-Zor, Syria, on Sunday, July 21.
Syrian civil war in photos —
A rebel fighter walks past swings in a deserted playground in Deir al-Zor, Syria, on Sunday, July 21.
karam jamal/reuters/landov
A rebel fighter speaks with a fellow fighter through a hole in a wall in Deir al-Zor on July 21.
Syrian civil war in photos —
A rebel fighter speaks with a fellow fighter through a hole in a wall in Deir al-Zor on July 21.
khalil ashaw/reuters/landov
A Free Syrian Army fighter casts a shadow on a wall as he carries his weapon in a shelter in Deir al-Zor on Thursday, July 18.
Syrian civil war in photos —
A Free Syrian Army fighter casts a shadow on a wall as he carries his weapon in a shelter in Deir al-Zor on Thursday, July 18.
Khalil Ashawi/Reuters/Landov
Yahya Sweed, 13, is comforted by his father as he lies on a bed in Kfar Nubul on Tuesday, July 16. The boy was injured by shrapnel, resulting in the amputation of his right leg.
Syrian civil war in photos —
Yahya Sweed, 13, is comforted by his father as he lies on a bed in Kfar Nubul on Tuesday, July 16. The boy was injured by shrapnel, resulting in the amputation of his right leg.
DANIEL LEAL-OLIVAS/AFP/Getty Images
A rebel fighter naps in a trench about 300 feet from the Syrian government forces' positions along the highway connecting Idlib with Latakia on Monday, July 15.
Syrian civil war in photos —
A rebel fighter naps in a trench about 300 feet from the Syrian government forces' positions along the highway connecting Idlib with Latakia on Monday, July 15.
DANIEL LEAL OLIVAS/AFP/Getty Images
A rebel fighter uses a hole in the wall of a destroyed school to aim at Syrian government forces in the Izaa district of Aleppo on Sunday, July 14.
Syrian civil war in photos —
A rebel fighter uses a hole in the wall of a destroyed school to aim at Syrian government forces in the Izaa district of Aleppo on Sunday, July 14.
M LOPEZ/AFP/Getty Images
A Free Syrian Army fighter uses a mirror to scope out snipers loyal to Syrian President Bashar al-Assad in Aleppo on Friday, July 12.
Syrian civil war in photos —
A Free Syrian Army fighter uses a mirror to scope out snipers loyal to Syrian President Bashar al-Assad in Aleppo on Friday, July 12.
MUZAFFAR SALMAN/reuters/LANDOv
A Free Syrian Army fighter stands over a boy who was injured during shelling in Al-Bara on Monday, July 8.
Syrian civil war in photos —
A Free Syrian Army fighter stands over a boy who was injured during shelling in Al-Bara on Monday, July 8.
DANIEL LEAL-OLIVAS/AFP/Getty Images
Members of the Free Syrian Army fire a homemade rocket toward regime forces in Deir al-Zor on Sunday, June 16.
Syrian civil war in photos —
Members of the Free Syrian Army fire a homemade rocket toward regime forces in Deir al-Zor on Sunday, June 16.
STRINGER/Reuters/LANDOV
Syrian rebels leave their position in the northwestern town of Maaret al-Numan on Thursday, June 13. The White House said that <a href="http://www.cnn.com/2013/06/13/politics/syria-us-chemical-weapons/index.html">the Syrian government has crossed a "red line"</a> with its use of chemical weapons and announced it would start arming the rebels.
Syrian civil war in photos —
Syrian rebels leave their position in the northwestern town of Maaret al-Numan on Thursday, June 13. The White House said that the Syrian government has crossed a "red line" with its use of chemical weapons and announced it would start arming the rebels.
DANIEL LEAL-OLIVAS/AFP/Getty Images
Forces loyal to Syrian President Bashar al-Assad are seen near Qusayr on Thursday, May 30.
Syrian civil war in photos —
Forces loyal to Syrian President Bashar al-Assad are seen ne