President Obama on Saturday authorized the use of limited military action against Libya, saying that continuing leader Moammar Gadhafi's attacks against his own people gave no other options the United States and its international allies.
Meanwhile, the Pentagon reported that 112 had already fired 20 cruise missiles against targets.
Obama said that military action was not his first choice.
"This is not an expected result that the United States or its allies. We can not sit still when a tyrant tells his own people will not have mercy" with them, "Obama said from Brazil, where he began a five-day visit to Latin America .
A senior military official said the United States launched air defense missiles on Saturday against the Libyan coast that were fired from Navy ships in the Mediterranean. The official said the attack could be carried out in stages and that aims to attack military defense installations around Tripoli, the capital of the country and in a coastal area south of Benghazi, the rebel enclave.
Obama said again that the United States would not send ground forces to Libya, but said he was "very aware" of the risks which contained the adoption of any military action.
Earlier in the day, Obama warned that the international community was ready to act with urgency.
"Our consensus was firm, our choice is clear. The people of Libya should be protected and in the absence of an immediate end to violence against civilians, our coalition is ready to act, and act with urgency," Obama said .
Senior officials of the United States, Europe and the Arab world gathered in Paris, where he announced on Saturday the immediate military action to protect civilians who are in the midst of fighting between forces and rebels Gadhafi. U.S. ships and planes were ready for action but did not participate in the first air raids led by the French.
At the time that military action was announced, French fighter jets flew over Benghazi, the enclave was attacked by opposition forces, the Libyan government on Saturday morning, in defiance of a truce had been proclaimed.
France, Britain and the United States warned on Friday that Gadhafi would come to military action if the Libyan head of state defied a United Nations resolution that called for a truce.
The United States has a strong group of soldiers and warships in the area, including submarines, destroyers, amphibious assault vehicles and boats arrive.
U.S. tries to limit his participation "at least in the early stages" to help protect French air missions designed to clear the Libyan air defenses, but depending on the response could be more attacks in support of allied forces, an official U.S..
