BAENGNYEONG ISLAND, South Korea - The Republic of Korea's (ROK) president ordered the military on alert Tuesday for any moves by rival, the Democratic People's Republic of Korea, after the defense minister said last week's explosion that sank a South Korean naval ship may have been caused by a DPRK mine.

The blast ripped the 1,200-ton ship apart last Friday night during a routine patrol near Baengnyeong Island near the tense maritime border west of the divided Korean Peninsula. Fifty-eight crew-members, including the captain, were plucked to safety; 46 are missing, with dim prospects for their survival.

A 53-year-old diver who lost consciousness during the underwater mission to locate the missing crewmen died Tuesday, the Joint Chiefs of Staff said. A second diver was being treated for injuries, officials said.