The U.S. role in the international effort in Libya is already starting to decline. According to a U.S. commander in the region, most of today’s missions over Libya were flown not by Americans, but by pilots from other countries in the coalition.

Gen. Carter Ham also says the international forces are planning to extend the no-fly zone to the Libyan capital of Tripoli. That’s hundreds of miles from the area where the most recent fighting has taken place between Moammar Gadhafi loyalists and the rebels trying to force him out.

Ham’s comments came hours before President Barack Obama told reporters in Chile that the U.S. will turn over leadership of the military operation to other countries within a “matter of days, not weeks.” Obama said Libyan leader Moammar Gadhafi “has to go,” but he says that’s not the goal of the international military effort against Libyan government forces.

The United States has fired close to 150 cruise missiles against Libyan targets in the past three days, including one that hit inside the compound in Tripoli where Gadhafi and his family live.

Speaking at a news conference during a visit to Chile, Obama said the strikes are carrying out the U.N. mandate to establish a no-fly zone over Libya and protect civilians from massacre by forces loyal to Gadhafi. Obama says Gadhafi has been “carrying out murders of civilians” and has “threatened more.”     

Libyan TV says the capital Tripoli hascome under a new attack by international airstrikes, now in their third night. Anti-aircraft fire erupted in the city several hours after nightfall Monday as television made the announcement. It was not immediately known what the strikes were targeting.

Meanwhile, four New York Times journalists who had been held captive in Libya for six days are free, and have crossed the border into Tunisia.

The four left Libya at the same dusty border crossing into Tunisia that has been used by tens of thousands of people fleeing violence. They are reporter Anthony Shadid, photographers Tyler Hicks and Lynsey Addario and videographer Stephen Farrell.

A spokesman for the Turkish Embassy in Washington says they were turned over to Turkey’s ambassador in Tripoli before making their way out of the country.

Libyan authorities said the journalists were captured last week by forces loyal to Col. Moammar Gadhafi during fighting in the eastern part of the country.

The New York Times reported that the four had entered the rebel-controlled area from Egypt without visas, as have many Western journalists.