12 moments in national security for President Obama's team

Updated 5:44 PM ET, Wed June 5, 2013
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Two explosions near the finish line of the Boston Marathon on April 15, 2013, killed three and injured more than 260 others. Tamerlan Suspect Tsarnaev died after a violent confrontation with police while his brother, Dzhokhar, was captured. Federal officials have declared the attacks an act of terror. As President Obama announces a new national security team, here is a look at key moments in national security since 2009: John Tlumacki/The Boston Globe via Getty Images
President Obama's administration has accelerated the use of remotely piloted military drones in surveillance and attacks on suspected terrorists. Ethan Miller/Getty Images
On May 2, 2011, under the cover of darkness, U.S. Navy SEALs entered the Abbottabad, Pakistan, complex of Osama bin Laden and killed the notorious terrorist leader. UPI/Sajjad Ali Qureshi/LANDOV
For much of 2013, North Korea has kept the rest of the world on edge as it threatened to launch missiles with nuclear warheads, although U.S. officials were skeptical of North Korea's ability to miniaturize a warhead enough to fit atop a missile. AFP/Getty Images
Uprisings across the Arab world in 2011 led to the toppling of governments in Tunisia, Egypt, Libya and Yemen, and threaten the regime in Syria. Peter Macdiarmid/Getty Images
In 2011, after nearly a year of bloody clashes with government troops, the regime of Libyan dictator Moammar Gadhafi fell and he was killed in October 2011. John Moore/Getty Images
U.S. Ambassador to Libya John Christopher Stevens and three other Americans were killed in an attack on the U.S. consulate in Benghazi, Libya. EPA/MUSTAFA EL-SHRIDI /LANDOV
A car bomb was discovered parked in the Times Square area of New York. Within hours, authorities took Faisal Shahzad into custody as the prime suspect.
Chris Hondros/Getty Images
The United States has accused China of trying to extract sensitive information from U.S. government computers in attacks launched from a military building inside China. Landov
Richard Phillips, captain of the Maersk Alabama cargo ship, was rescued after U.S. Navy sharpshooters killed his Somali pirate captors. Jon Rasmussen/U.S. Navy via Getty Images
As one of his first acts as president, Obama signed an executive order to close the Guantanamo Bay detention center, but resistance in Congress has kept the facility open. In May 2013, Obama renewed his intention to shut down the facility. John Moore/Getty Images
The last U.S. troops in Iraq crossed the border into Kuwait on December 18, 2011, ending an eight-year war in the troubled nation. Joe Raedle/Getty Images