WASHINGTON Flexing its military muscle, the United States sent warships toward Libya on Tuesday as it sought to keep pressure on Muammar Gaddafi to relinquish his four-decade grip on power.
Secretary of State Hillary Clinton said the United States and its NATO allies were still considering a "no-fly" zone over Libya, although military commanders warned of the peril to allied aircraft of enforcing it.
The United States has also frozen $30 billion in Libyan assets.
"We are going to keep the pressure on Gaddafi until he steps down and allows the people of Libya to express themselves freely and determine their own future," Susan Rice, the U.S. ambassador to the United Nations, told ABC's "Good Morning America" program.
Two amphibious assault ships -- the USS Kearsarge, which can carry 2,000 Marines, and the USS Ponce -- were due to sail through the Suez Canal and enter the Mediterranean Sea early on Wednesday morning, an Egyptian official said.
The repositioning of U.S. ships and aircraft closer to Libya is widely seen as a symbolic show of force since neither the United States nor its NATO allies have shown any appetite for direct military intervention in the turmoil that has seen Gaddafi lose control of large swaths of his country.
U.S. officials said the ships were being redeployed in preparation for possible humanitarian efforts as tens of thousands of people flee the violence. But they said military action remained an option.
"We are looking at a lot of options and contingencies. No decisions have been made on any other actions," Defense Secretary Robert Gates said, noting the United Nations had not authorized the use of force in Libya.
As of Tuesday, there were three U.S. ships in the Mediterranean -- two destroyers and the USS Mount Whitney, the command ship of the U.S. Sixth Fleet based in Gaeta, Italy.
Gates declined to comment on reports the USS Enterprise, an aircraft carrier in the Red Sea, could be moved into the Mediterranean, a step that would significantly augment the U.S. military presence off Libya.
CIVIL WAR FEARS
Clinton warned of civil strife if Gaddafi, whose forces are trying to regain control of areas now in rebel hands, refused to step down.
"In the years ahead, Libya could become a peaceful democracy or it could face protracted civil war, or it could descend into chaos," she told U.S. lawmakers.
Clinton also said U.S. authorities would look into claims that Gaddafi may have ordered the 1988 bombing of Pan Am Flight 103 over Lockerbie that killed 270 people. Libya accepted civil responsibility for the bombing in 2003 but Gaddafi has never been held to account.
Rice said the United States would work to stabilize oil prices, which jumped to their highest in 2 1/2 years on unrest in the oil-producing North African country. "This ... does have potential implications for oil supply, oil prices," she said.
Some Republican lawmakers have criticized the Obama administration's initially cautious response to the Libyan crisis and pressed it to impose a no-fly zone.
That would prevent Gaddafi from using his air force against the rebels, although analysts say the Libyan leader has been relying mainly on ground forces to attack opponents.
Admiral Mike Mullen, chairman of the Joint Chiefs of Staff, said a no-fly zone would be a highly complex operation.
"If we were to set it up ... we'd have to work our way through doing it in a safe manner and not put ourselves in jeopardy," he said.
Libya's Air Defense Command is estimated to have at least 216 surface-to-air missiles and 144 towed and 72 self-propelled missiles. But many analysts say much of Libya's military equipment is poorly maintained or unusable, raising questions about what threat the anti-aircraft missiles would pose.
(Additional reporting by David Morgan, Alister Bull, Steve Holland, Jeff Mason and Susan Cornwell; Writing by Ross Colvin; Editing by John O'Callaghan and Philip Barbara)