U.S. military in Gulf on highest state of alert

WASHINGTON (CNN) -- U.S. officials said Friday that the U.S. military has moved to its highest state of alert in the Persian Gulf region on the basis of a credible, but nonspecific, threat against U.S. interests.

The threat was not necessarily against U.S. military interests, they said.

State Department officials tell CNN they plan to reissue a worldwide caution, reflecting new information about increased threats to Americans overseas.

MESSAGE BOARD Security threats

The U.S. Fifth Fleet was on Threat Con Delta, meaning a terrorist attack was considered imminent, and all its ships were sent to sea.

The procedure to move ships out of ports was instituted after the attack last year on the USS Cole. The intent is to make the vessels less vulnerable.

The U.S. carrier group Constellation is in the Gulf region now.

There is a strong belief that the threat may be linked to Thursday's indictment of 14 people for the 1996 Khobar Towers bombing in Saudi Arabia.

Next week is also the fifth anniversary of that attack.

CNN Pentagon Correspondent Jamie McIntyre and CNN National Security Correspondent David Ensor contributed to this report.