LINDA WERTHEIMER, host:
This week NATO takes over command of enforcing Libya's no-fly zone. Here in Washington, the secretary of state and the secretary of defense are defending President Obama's handling of the situation. But critics from both parties are pressing for more information on the role of the U.S. in the larger military operation, and on how long it will take, as well as why the president didn't come to Congress first.
NPR's Don Gonyea reports.
DON GONYEA: The U.S. military operation in Libya started nine days ago. Since then, President Obama has faced criticism from Republicans and from some Democrats for not having stated firm goals and for not getting congressional approval first.
Tonight's speech will be his first major attempt to explain. He offered a preview in his weekly address on Saturday, saying the U.S. should not and cannot intervene every time there's a crisis somewhere in the world.
President BARACK OBAMA: But I firmly believe that when innocent people are being brutalized, when someone like Gadhafi threatens a bloodbath that could destabilize an entire region, and when the international community is prepared to come together to save many thousands of lives, then it's in our national interest to act.
GONYEA: Yesterday, Secretary of State Hillary Clinton and Defense Secretary Robert Gates made the case in joint appearances on the Sunday morning network news programs.
On NBC's "Meet the Press," Gates was asked if Libya fits the definition of a vital U.S. interest.
Secretary ROBERT GATES (Department of Defense): No, I don't think it's a vital interest for the United States, but we clearly have interests there, and it's a part of the region which is a vital interest for the United States.
GONYEA: Secretary of State Clinton quickly followed, stating that the U.S. is acting as a member of NATO, pointing out that when the U.S. asked for NATO allies to join the war in Afghanistan following 9/11, they responded.
Secretary HILLARY CLINTON (Department of State): When it comes to Libya, we started hearing from the U.K., France, Italy, other of our NATO allies. This was in their vital national interest.
GONYEA: On "Meet the Press," Senator Richard Lugar says the president should have sought congressional approval. And...
Senator RICHARD LUGAR (Republican, Indiana): There must be a plan, there must be objectives, the end game, what we want to achieve, and then at least some means as to how that's going to occur. That has not happened as yet.
GONYEA: The chairman of the Senate Armed Services Committee, Democrat Carl Levin, was on CNN. He backed up the White House on Libya, adding that the no-fly zone is working.
Senator CARL LEVIN (Democrat, Michigan): It has set Gadhafi back. He's on his heels now, moving his troops towards his capital, where he's strong. But it has prevented the slaughter of Libyan people, and that is what the trigger was for the president.
GONYEA: Yesterday, NATO announced that it's taking over command of the operation. That's something the president will be emphasizing tonight.
But Secretary Gates, while stressing that U.S. ground forces will not be deployed to Libya, also said yesterday it's impossible to say if the U.S. military will still be involved in Libya at year's end.
And there's the wider ongoing unrest in the region that presents more unknowns. That's something Republican Senator John McCain cautioned about on "Fox News Sunday." He cites Yemen as just one example.
Senator JOHN MCCAIN (Republican, Arizona): Yemen is entirely different. This is going to be a huge problem, because it is basically a tribal society, as you know, cobbled together, the country, by the British. And so it's going to be very difficult in some of these countries.
GONYEA: McCain said he feels good about the chances of democracy taking hold in Tunisia and Egypt. Elsewhere there are huge questions, he said, noting that every country is different.
Don Gonyea, NPR News, Washington.