By Alister Bull and Missy Ryan
BRASILIA/WASHINGTON (Reuters) - U.S. forces joined those of four other countries in launching strikes against Libya on Saturday and President Barack Obama insisted U.S. involvement was limited and only in support of an international effort.
The United States, France, Britain, Canada and Italy began attacks on targets designed to cripple Muammar Gaddafi's air defenses as the West tries to force the Libyan leader from power. At least some Arab nations are expected to join the coalition.
French planes fired the first shots in the biggest international military intervention in the Arab world since the 2003 invasion of Iraq, destroying tanks and armored vehicles in eastern Libya. Hours later, U.S. and British warships and submarines launched more than 110 Tomahawk cruise missiles against air defenses in the oil-producing North African country.
In announcing the missile strikes, which came eight years to the day after the 2003 U.S.-led invasion of Iraq, Obama said the effort was intended to protect the Libyan people.
"Today I authorized the armed forces of the United States to begin a limited action in Libya in support of an international effort to protect Libyan civilians. That action has now begun," Obama told reporters in Brasilia, where he had just begun a five-day tour of Latin America.
He said U.S. troops were acting in support of allies, who will lead the enforcement of a no-fly zone to stop Gaddafi's attacks on rebels.
"As I said yesterday, we will not, I repeat, we will not deploy any U.S. troops on the ground," Obama said, grim-faced as he delivered the news of U.S. military action in a third Muslim country.
After Obama spoke, Vice Admiral Bill Gortney, director of the U.S. military's Joint Staff, described the U.S. role by saying, "We are on the leading edge of a coalition military operation. This is just the first phase of what will likely be a multiphase operation."
Gortney said the missile strikes were only the first phase of a multiphase action.
The New York Times quoted NATO officials as saying France and Britain would run the initial phase with U.S. help and that by midweek NATO would take up the role of enforcing a no-fly zone and arms embargo.
"HOLLOW WORDS" FROM LIBYA
The Obama administration had taken a lower profile in diplomacy leading to the U.N. resolution that set up the strikes, believing that it would allow Arab states to coalesce around a call for action and deny Gaddafi the chance to argue that the United States was leading another attack on Muslims.
"This is not an outcome that the United States or any of our partners sought. Even yesterday, the international community offered Muammar Gaddafi the opportunity to pursue an immediate ceasefire, one that stopped the violence against civilians and the advances of Gaddafi's forces.
"But despite the hollow words of his government, he has ignored that opportunity," Obama said.
Aides said there were no plans for Obama to cut his trip short.
U.S. forces and planes will take part in the operation, called Odyssey Dawn, which will mainly target air defenses around the Libyan cities of Tripoli and Misrata.
Some 25 coalition ships, including three U.S. submarines armed with Tomahawk missiles, are stationed in the Mediterranean, a military slide showed. Five U.S. surveillance planes also are in the area.
The United States is already enmeshed in long wars in Afghanistan and Iraq and there is little appetite in Congress and among the public for another expensive military intervention.
U.S. officials have said repeatedly that it is time for Gaddafi to leave but lately have stressed that the goal of military action in Libya was different.
"It is to protect civilians and it is to provide access for humanitarian assistance," Secretary of State Hillary Clinton said in Paris, where she attended a conference called by French President Nicolas Sarkozy to discuss the international response to the Libya crisis.
One of Obama's deputy natural security advisers, Denis McDonough, called Republican and Democratic congressional leaders to brief them on the military action. Obama had discussed the crisis in Libya with congressional leaders at the White House on Friday before issuing his ultimatum.
(Additional reporting by Matt Spetalnick in Brasilia, Phil Stewart and Mark Felsenthal in Washington and Andrew Quinn in Paris; Writing by Patricia Zengerle; editing by Doina Chiacu and Bill Trott)