The Army believes chemical weapons dumped in deep water five miles south of Pearl Harbor after World War II should stay where they are.

Army officials on Friday said that removing the munitions may increase the risk of exposure to humans and the environment.

The University of Hawaii earlier said the weapons don’t currently pose a threat but are deteriorating and should continue to be monitored.

The report was based on a three-year study of munitions found up to 2,000 feet below the surface.

Historic records show the Army dumped 16,000 bombs at the site through 1970. Each of the bombs contained 73 pounds of the chemical agent mustard.