The identities of the Americans were not immediately known, but the yacht, the S/V Quest, is owned by Jean and Scott Adam, according to Ecoterra International, a piracy watchdog group.

It is not clear whether the Adams - who were on a worldwide cruise - are onboard.

The U.S. military is prepared to intervene in the situation if necessary, said Rear Adm. Charles Gaouette, deputy commander of the U.S. Navy's Fifth Fleet, based in Bahrain.

"They were part of a sailing group that set sail from the southern tip of India into the western Indian Ocean," he said, adding that the situation is being monitored with U.S. Central Command.

Gaouette said there is no reason to believe the hijacked yacht has been taken to the coastline of Somalia yet, though pirates in the region have been known to do so.

Another U.S. official, who asked not to be named due to the sensitivity of the situation, said the United States is determining what military assets are in the region and the capabilities of the personnel onboard. The official said that the pirates are believed to be on board the yacht with the Americans, and the next step would be to determine with the military could keep the yacht from reaching the shore -- either by blocking or harassing it.

Authorities said the yacht was en route from India to Oman when it was captured on February 18.