US Gulf fleet puts to sea after security alert

US forces in Bahrain, home of the Navy’s Fifth Fleet in the Gulf, are on a heightened state of alert in response to a security threat.

A US defence official said the decision to take extra security precautions was not related to the convictions of four men for the bombing of US embassies in Africa. The four are followers of expatriate Saudi fugitive Osama bin Laden.

The official declined to say what triggered the decision to raise the alert level on Bahrain to threat condition ‘‘Charlie’’, the second highest level.

He said it was done early this week in response to a threat, but he would not elaborate.

Much of the Fifth Fleet was put to sea as a precaution, he said.

At US Central Command, which oversees military operations in the Gulf, spokesman Lieutenant Colonel Mark Samisch declined to comment. ‘‘We’re not talking about any threat conditions,’’ he said.