NORFOLK, Va. (AP) -- The former commander of the USS Sterett says his orders were to prevent a band of Somali pirates from taking four American hostages with them to shore, but that his crew wasn't authorized to use lethal force.

Cmdr. Darren McPherson testified in federal court in Norfolk Friday that he specifically told his crew not to fire at the yacht Quest even if the pirates fired at his ship. McPherson says the risk of harming the Americans was too great.

The yacht's owners, Jean and Scott Adam of Marina del Rey, Calif., and their friends, Bob Riggle and Phyllis Macay of Seattle, were fatally shot in February 2011 several days after they were taken hostage several hundred miles south of Oman.

Three Somalis are on trial for murder and other charges.