Groton - The USS Providence is leaving the coast of Libya after firing Tomahawk cruise missiles on the war-torn north African nation, U.S. Sen. Richard Blumenthal, D-Conn., said Tuesday.

American and British ships and submarines launched a missile assault on Libyan air defenses Saturday, firing 112 Tomahawk cruise missiles at more than 20 coastal targets in support of a no-fly zone.

The number of Tomahawk cruise missiles launched has since climbed to more than 160, according to the Navy, as Libyan leader Moammar Gadhafi has continued his attacks on rebels.

Each missile costs between $1.3 million and $1.4 million, a Navy spokesman said.

After touring the Naval Submarine Base, which is home to the Providence, Blumenthal said Tuesday that he was told at the base that the submarine is returning while the USS Florida and USS Scranton remain near Libya.

"I want to thank the Providence for the great work," Blumenthal said.

The Navy would not confirm the location of the Providence. It typically does not reveal details about submarine movements or future operations.

Submarines such as the Providence can help prevent potential "mission creep," or the expansion of a project or mission beyond its original goals, in the military operation in Libya, said Blumenthal, who toured the USS Hartford (SSN 768) at the base. The Hartford's weapons and fire control systems are similar to those on the Providence (SSN 719). Both are Los Angeles-class submarines.

The capabilities of these submarines, Blumenthal said, enable the military to achieve goals that could otherwise require troops on the ground in Libya.

Blumenthal stressed the importance of U.S. forces operating as part of the international coalition that will increasingly take over control of the airspace.

"We're engaged in two very costly wars now, costly in dollars and in human commitments," he said. "We need to avoid the mission creep that is always a danger."

Both Blumenthal and U.S. Rep. Joe Courtney, D-2nd District, have said they support using U.S. forces in Libya only on a short-term, limited-scope basis.

In 2003 the Providence fired missiles into Iraq from the Red Sea. Eighteen months earlier, the sub had fired some of the opening shots against the Taliban regime in Afghanistan.

j.mcdermott@theday.com