2 U.S. carrier groups show Iran their muscle

The drills involved 15 ships and more than 100 aircraft. Iran has frequently condemned the U.S. military presence and is in a dispute with the West over its nuclear program and its capture Friday of 15 members of a British naval team.

In London on Tuesday, Prime Minister Tony Blair warned that his government could make public evidence that a British navy crew was in Iraqi waters — not Iranian — when it was captured by Iran, saying he was prepared to take the standoff to a "different phase" if diplomacy fails to win their release.

Iran said the 15 British sailors and marines were being treated well, but refused to say where they were being held or rule out the possibility that they could be brought to trial for allegedly entering Iranian waters.

"I hope we manage to get them to realize they have to release them," Blair said in a TV interview. "If not, then this will move into a different phase."

Blair's spokesman said the prime minister was not hinting at expulsion of Iranian diplomats or military action.

U.S. commanders insisted the Persian Gulf exercises were not a direct response to Iran's seizure of the Britons, but they also made clear that the flexing of the Navy's military might was intended as a warning.

"If there is strong presence, then it sends a clear message that you better be careful about trying to intimidate others," said Capt. Bradley Johanson, commander of the Stennis.

"Iran has adopted a very escalatoryk posture with the things that they have done," he added.

The exercises began four days after Iranian forces detained the Britons for allegedly being in Iranian waters near the northern end of the Gulf. U.S. and British officials insist the team was properly searching cargo vessels inside Iraqi waters.

F/A-18 fighters roared off the Stennis' flight deck all day, mounting a dozen sorties against imaginary enemy ships and aircraft. A second task force with the carrier USS Dwight D. Eisenhower also took part.