Obama announced that NATO would take command over the entire Libya operation on Wednesday, keeping his pledge to get the U.S. out of the lead - but offering no estimate on when the conflict might end.
He never described the U.S.-led military campaign as a "war" and gave no details on its costs, but he offered an expansive case for why he believed it was in the national interest of the United States and allies to act.
In blunt terms, Obama said the U.S.-led response had stopped Gadhafi's advances and halted a slaughter he warned could have shaken the stability of an entire region.
"To brush aside America's responsibility as a leader and - more profoundly - our responsibilities to our fellow human beings under such circumstances would have been a betrayal of who we are," Obama said. "Some nations may be able to turn a blind eye to atrocities in other countries. The United States of America is different. And as president, I refused to wait for the images of slaughter and mass graves before taking action."
Obama spoke to a respectful military audience at the National Defense University after, in Libya, rebel forces bore down Monday on Gadhafi with the help of airstrikes by the U.S.-led forces. The address to the nation was the president's most aggressive attempt to answer the questions mounting from Republican critics, his own party and war-weary Americans - chiefly, why the U.S. was immersed in war in another Muslim nation.
Amid protests and crackdowns across the Middle East and North Africa, Obama stated his case that Libya stands alone. "In this particular country, at this particular moment, we were faced with the prospect of violence on a horrific scale," he said.
He also warned of the broader implications for the region, without naming the other countries undergoing violent upheaval.
Citing a failure to act in Libya, he said: "The democratic impulses that are dawning across the region would be eclipsed by the darkest form of dictatorship, as repressive leaders concluded that violence is the best strategy to cling to power. The writ of the U.N. Security Council would have been shown to be little more than empty words, crippling its future credibility to uphold global peace and security."