Obama praises Boston cops, says bombers have ‘already failed’

President Barack Obama late Friday praised Boston police and law enforcement cooperation for their week-long response to the Boston Marathon bombings and acknowledged "many unanswered questions" about what drove the suspects to violence. But he emphasized that the alleged terrorists have "already failed" if they sought to divide America.

"Tonight, our nation is in debt to the people of Boston and the people of Massachusetts," Obama said in hastily arranged public remarks in the White House briefing room. "After a vicious attack on their city, Bostonians responded with resolve and determination. They did their part as citizens and partners in this investigation.

"Obviously, tonight, there are still many unanswered questions. Among them: Why did young men who grew up and studied here as part of our communities and our country resort to such violence? How did they plan and carry out these attacks? And did they receive any help?" he said, in the clearest-yet suggestion that violence might have had roots overseas. The families of those killed and those who were wounded "deserve answers," he said, and federal law-enforcement agencies will deploy "all the necessary resources" to give them that satisfaction.

"We will determine what happened. We will investigate any associations that these terrorists may have had. And we’ll continue to do whatever we have to do to keep our people safe," Obama said.

"One thing we do know is that whatever hateful agenda drove these men to such heinous acts will not, cannot prevail. Whatever they thought they could ultimately achieve, they’ve already failed," the president said. "They failed because the people of Boston refused to be intimidated. They failed because as Americans we refuse to be terrorized. They failed because we will not waive from the character, and the compassion, and the values that define us as a country, nor will we break the bonds that hold us together as Americans."

Obama received repeated briefings from his national security team all week—ever since bombs ripped through the crowd near the Boston Marathon's finish line on Monday. On Friday, the White House let it be known that he had been briefed overnight and throughout the day. There was one major shift: CIA Director John Brennan for the first time was numbered among the top officials who discussed the crisis with Obama. And the president also discussed the crisis with Russian President Vladimir Putin—likely because the suspects were apparently of Chechen origin. Russia has waged war on Chechnya for decades, and the conflict served as a training ground for Islamist extremist fighters.

Obama also assured the people of West, Texas, coping with the aftermath of a massive explosion at a fertilizer plant, that “they are not forgotten.

"All in all, this has been a tough week. But we have seen the character of our country once more," he said.

"As president, I’m confident that we have the courage, and the resilience, and the spirit to overcome these challenges and to go forward as one nation, under God, indivisible, with liberty and justice for all."

Earlier, Obama called Massachusetts Gov. Deval Patrick and Boston Mayor Tom Menino on Friday afternoon to express his condolences for an MIT police officer killed overnight during a manhunt for the suspects, according to a White House official.

MIT police officer Sean Collier, 26, of Somerville, Mass., was shot and killed during the manhunt, and another police officer, Richard H. Donahue Jr., 33, was shot and is in stable condition at Mt. Auburn Hospital, according to the Boston Globe.