In the western city of Misurata, forces loyal to Colonel Qaddafi were still at large and were using civilians as human shields, Reuters reported, but that could not be immediately confirmed.

At the Pentagon, officials said that the intensive American-led assault unleashed over the weekend was a classic air campaign, chosen by Mr. Obama among a range of military options, which was intended to have coalition aircraft in the skies above Libya within days and without fear of being shot down. “You don’t do that piecemeal,” a United States military official said. “You do it all at once, and you do it as fast as you can.”

The targets included radar installations, fixed and mobile antiaircraft sites, Libyan aircraft and hangars, and other targets intended to make it safe for allied aircraft to impose the no-fly zone. They also included tanks and other ground forces engaged with the rebels around the country, reflecting the broader aim of pushing Colonel Qadaffi’s forces to withdraw from disputed cities. Communications centers and at least one Scud missile site were also struck.

Explosions and antiaircraft fire could be heard in and around Tripoli on Monday in a third straight night of attacks there against Colonel Qadaffi’s forces.

United States military officials said that there were fewer American and coalition airstrikes in Libya on Sunday night and Monday, and that the number would probably decline further in coming days. But Gen. Carter F. Ham, the head of the United States Africa Command, who is in charge of the coalition effort, said that there would be strikes on Colonel Qaddafi’s mobile air defenses and that some 80 sorties — only half by the United States — were flown on Monday.