MANAMA, Bahrain (AP) _ The aircraft carrier USS America was reported today to have resumed patrol off the coast of Iran, putting another powerful military force at President Bush's disposal in the Lebanon hostage crisis.

The nine-ship battle group was in Singapore, nearly 4,000 miles away, when the crisis arose July 31 with the reported hanging of U.S. Marine Lt. Col. William R. Higgins by his Lebanese Shiite captors and a death threat against a second American hostage.

The America cut short its port visit by four days to return to its assigned duty station in the north Arabian Sea, a voyage requiring nearly a week.

U.S. officials refused, as a matter of policy, to discuss ship movements, but Defense Secretary Dick Cheney told reporters in Washington that the carrier was headed for the ''north end of the Indian Ocean.''

A convoy located in the Arabian Sea, or further south in the Indian Ocean, could steam north through the Gulf of Oman and enter the Persian Gulf.

A Pentagon spokesman said on Tuesday that the America was ''conducting routine operations'' in the Indian Ocean but would not say where. Other sources, speaking on condition of anonymity, said it was resuming normal duties in the north Arabian Sea.

The battle group was deployed in June to the Navy's Joint Task Force Middle East, the only U.S. surface fleet operating within striking distance of Iran. The force also includes 10 ships in the Persian Gulf.

The 79,000-ton America's port call at Singapore had been scheduled well in advance, and a military source called it ''just the breaks'' that the hostage crisis arose during its absence.

U.S. warships in the gulf region have operated at reduced alert status and spent more time in port since Iraq and Iran agreed last year to a cease-fire in their eight-year war.

Administration sources in Washington have been quoted as saying Bush had opted for a military reprisal if any more hostages were killed. They said he would probably use planes from the carrier USS Coral Sea in the eastern Mediterranean to strike suspected terrorist strongholds in Lebanon.

However, the sources have not ruled out an attack on Iran, which is considered to wield great influence over Shiite Moslem groups holding Western hostages in Lebanon.

In that event, the America and its more than 80 combat aircraft would be the probable choice.

Military analysts agreed that the most logical target for military action against Iran would be its big oil terminal at Kharg Island, 500 miles northwest of the Strait of Hormuz, the gulf outlet to the Arabian Sea.

For the U.S. planes, it would mean dodging the terminal's anti-aircraft defenses that downed a number of Iraqi planes during the war.

The U.S. warships in the gulf are designed mainly for missile war against aircraft, ships and submarines. Their 5-inch and 76-mm guns would be hard put to inflict more than token damage on a sprawling complex like Kharg Island.

Military sources ruled out any use of the Coral Sea against Iran, noting that its planes would have to make a 3,000-mile round trip through the airspace of several countries.