DUBAI, United Arab Emirates — U.S. Navy sailors aboard a supply vessel acted within rules of engagement last year when they fired on a small boat approaching at high speed off Dubai, killing one Indian fisherman and wounding three others, according to a Navy investigation made public today.

The July 2012 incident has been described by Navy officials as “regrettable,” but it also highlighted the heightened security to protect vessels following boat-borne blasts such as the 2000 suicide attack on the USS Cole in Yemen that killed 17 U.S. sailors and the 2004 explosion of a dhow in Persian Gulf that killed three crew members of the USS Firebolt.

The U.S. Navy 5th Fleet, based in Bahrain, has taken steps to expand security escorts for port-bound U.S. ships and worked with Gulf officials to distribute fliers in several languages advising to stay clear of Navy vessels.