The United States government announced that it has launched a review of the handling and sharing of intelligence prior to the Boston Marathon attacks.
The Inspectors General of the Intelligence Community said it had "initiated a coordinated and independent review into the US government's handling of intelligence information leading up to the Boston Marathon bombings,” the AFP news agency reported.
The review "will examine the information available to the US government before the bombings and the information sharing protocols and procedures followed between and among the intelligence and law enforcement agencies."
The Central Intelligence Agency, the Department of Justice and the Department of Homeland Security will also take part in the review.
US lawmakers and others have questioned why the suspected mastermind of the attack, Tamerlan Tsarnaev, 26, who was killed in a police shootout, did not raise more red flags in the years prior to the bombing.
The Federal Bureau of Investigation (FBI) questioned Tsarnaev, an ethnic Chechen, at Russia's request in 2011, but did not conclude he was a threat.
The following year Tsarnaev, who appears to have posted radical Islamist videos on social media, traveled to the volatile North Caucasus region of Russia, home to several fierce Islamist and separatist groups for six months.
Tsarnaev and his younger brother Dzhokhar are accused of going on to carry out the April 15 bombing at the Boston Marathon, which killed three and wounded more than 264 at one of the world's premier sporting events.
Earlier Tuesday, Obama defended the FBI and said US authorities had done the best they could in the face of threats that include what he called "self-radicalized individuals."
"Based on what I've seen so far, the FBI performed its duties, the Department of Homeland Security did what it is was supposed to be doing. But this is hard stuff," Obama told a news conference, according to AFP.
He added that Russia had been very cooperative in the post-bombing probe, but acknowledged lingering suspicions between the intelligence and law enforcement agencies of the two former Cold War foes.
"You know, old habits die hard," Obama said.
Tamerlan Tsarnaev was killed in a shootout with police as he tried to flee the Boston area three days after the bombing. His younger brother was wounded and captured, and now faces terror charges carrying a possible death sentence.