US president Barack Obama defended his country's military action in Libya and indicated that it would now move to a supporting role in the intervention.
In a speech early today designed to build up popular opinion about the action, Mr Obama said the US was fulfilling its pledge to have a "limited role" in the operation.
"For those who doubted our capacity to carry out this operation, I want to be clear -- the United States of America has done what we said we would do," he said.
Mr Obama said Nato -- which has already taken over responsibility for enforcing the arms embargo and no-fly zone -- would take full command of all military operations from tomorrow.
Justifying the military action in recent weeks, the president conceded that the US could not use its armed forces "wherever repression occurs", but stressed that, in this instance, "we were faced with the prospect of violence on a horrific scale".
He added: "To brush aside America's responsibility as a leader and more profoundly our responsibilities to our fellow human beings in other such circumstances would have been a betrayal of who we are."
He said he was "convinced" a failure to act would have "carried a far greater price for America".
While he said there was "no question" Libya and the world would be better off without Gaddafi in power, he stressed he would "actively pursue that goal through non-military means".
"But broadening our military mission to include regime change would be a mistake," Mr Obama added.