(CNN) -- The back-and-forth continued Wednesday on the battlefield, across the political spectrum and in the skies over Iraq, where the simmering unrest shows no sign of abating.
Here are some key developments over the course of the day:
U.S. military advisers begin work
U.S. military advisers are in Iraq, and they sat down with Iraq's various security forces, said Iraq's military spokesman, Maj. Gen. Qassim Atta.
"The advisers have been distributed in groups to the Defense Ministry, the Interior Ministry, the Baghdad operations center and the counterterrorism unit," Atta said.
Ninety of the 300 advisers promised by U.S. President Barack Obama arrived this week, and another 40 working the U.S. Embassy have been reassigned to advise, the Pentagon said earlier this week.
The road to Samarra
Security forces control the road from Baghdad to Samarra, home of a revered Shiite shrine, Atta said during a televised briefing.
"We are continuing the operation to cleanse Samarra" province, he said.
Samarra sits 100 kilometers (62 miles) north of Baghdad, and is significant to Shiites for its al-Askari mosque. ISIS fighters, who are receiving support from Sunni tribes, have threatened to destroy any shrine they deem un-Islamic.
An attack on the mosque in 2006 was ground zero for the sectarian fighting that pushed the country to the verge of civil war, and many fear another such attack would push Iraq to the breaking point.
Kirkuk car bomb
A car bomb exploded at an outdoor market in northern Kirkuk on Wednesday, killing at least six people and wounding 21, police officials told CNN.
The explosion occurred in the predominantly Kurdish neighborhood of Rahimawa, the officials said.
Kirkuk is an ethnically mixed city of Sunni, Shiite, Kurds and Turkmen, who all lay claim to the oil-rich city that sits 260 kilometers (162 miles) north of Baghdad.
Kerry on Iran's involvement
U.S. Secretary of State John Kerry declined to comment on Iran's intention toward Iraq, saying, "Frankly, you should best direct that question to Iran and the government of Iraq.
"But from our point of view we have it clear to everyone in the region that we don't need anything to take place that might exacerbate the sectarian divisions that are already at a heightened level of tension, and so it is very important that nothing takes place that contributes to the extremism or could act as a flashpoint with respect to the sectarian divide," Kerry told reporters.
The secretary's comments come as the conflict in Iraq has widened amid reports of Syrian airstrikes and Iranian involvement.
"It's been widened obviously in the last days with the reports of IRGC personnel, some people from Iran being engaged in Iraq, with perhaps even some Syrian activities therein, and that's one of the reasons why government formation is so urgent," he said.
"...President Obama is very, very clear that our priority is that government formation, and we are going to take every step we can over the next days."
A U.S. official told CNN that Iran is flying surveillance drones over Iraq. Iran is believed to be providing small arms and ammunition to Iraq, as well as providing intelligence to the government, the official said.
Reports that Syrian warplanes conducted a cross-border attack on Iraqi towns this week is further evidence of the blurring between the two countries' borders as they face an offensive by Islamic extremists.
At least 57 Iraqi civilians were killed and more than 120 others were wounded by what local officials say were Syrian warplanes that struck several border areas of Anbar province Tuesday.
These border cities are among those under the control of the Islamic State in Iraq and Syria, the al Qaeda offshoot also known as ISIS.
The airstrikes hit markets and gas stations in Iraqi border areas such as Rutba, al-Walid and Qaim, Sabah Karkhout, the head of the provincial council, said Wednesday.
"Unfortunately, (the) Syrian regime carried out barbarian attacks against civilians in Anbar province," Karkhout said. "Today we will hold an emergency meeting in Ramadi to address this issue."
Iraq's military spokesman, Atta, denied reports that Syrian warplanes struck inside Iraq's border towns.
"We know our airspace. We have not recorded or registered infiltration of our air space from foreign jets, and all the warplanes and helicopters flying over Iraq airspace are Iraqis," he told CNN.
Syrian state media called the reports of a cross-border incursion "completely baseless" allegations made by "malicious media outlets," citing a "Syrian media source."
Karkhout said he was certain the warplanes were Syrian because they bore the image of a Syrian flag. "Also, the planes flew directly from Syrian airspace and went back to Syria," he said.
Local officials used scopes and other equipment to see details on warplanes.
All intelligence indicates that Syrian warplanes struck targets inside Iraq, a Western official told CNN.
The motive and intent of the strikes are not clear, and it is also "unclear" whether there is some agreement or partnership between the Syrian and Iraqi governments for these strikes, the official said on the condition of anonymity.
Al-Maliki shows no sign of leaving
In a televised speech, Prime Minister Nuri al-Maliki vowed to stick to the timeline to create a new government, saying a call for the formation of a "national salvation government" -- akin to an emergency government -- "represents a coup against the constitution and the political process."
"I say clearly and with all honesty, that despite the ferocity of the battle against terrorists, we will continue to be loyal and dedicated to the will of the Iraqi people and their democratic path and the protection of the political process," he said.
"We will attend the first session for Parliament in accordance to constitutional rights."
Kerry downplayed al-Maliki's rejection of a salvation government, saying it wasn't something the United States had talked to him about specifically.
Atta calls for sanctions against media organizations
Rejecting reports that Baiji oil refinery had fallen into the hands of ISIS, Maj. Gen. Atta called for sanctions against news agencies, particularly the Saudia Arabia-based Al Arabiya.
"From my place standing here, I'm calling on the national communication council to take all the necessary steps," Atta said.
Coffee shop attack
A suicide bomber and a mortar attack targeted a popular coffee shop and other buildings in Mahmoudiya, about 35 kilometers south of Baghdad, killing 12 people and wounding 46 on Wednesday, police officials told CNN.
The suicide bomber struck the coffee shop first, and that was followed by a mortar attack that targeted several buildings in the area, the officials said.
Helicopter attack kills civilians
An Iraqi military helicopter opened fire in Ana in Anbar province on Wednesday, killing six people, including two children and a doctor, police and health officials told CNN.
The officials claim the helicopter fired two rockets, with one hitting a mosque and the other striking a nearby house.
At least 21 people, most of them children between the ages of 6 and 12, were wounded in the airstrike, they said. Most of those wounded were at the mosque attending a Quran study session, according to one the health officials.
But health and police officials in Ramadi told CNN that an Iraqi military helicopter targeted a building used by militants in nearby Haditha. A casualty count was not immediately available, the officials said.
Ana was among a handful of towns reportedly seized by ISIS fighters over the weekend, during the terror group's advance in Anbar. Ana sits 330 kilometers (205 miles) northwest of Baghdad.