The former captain of the U.S. Navy submarine that in 2001 collided with a Japanese high school fishing training boat off Hawaii on Tuesday made public his letter of apology to the families of those killed in the incident.

Marking the 20th anniversary of the fatal accident, retired Cmdr. Scott Waddle, 61, who was in charge of the 6,080-ton nuclear submarine Greeneville, wrote he is "solely responsible" for the Feb. 9, 2001, collision that sank the 499-ton Ehime Maru, killing nine of the 35 people aboard.

The 8-page open letter, dated Tuesday, was addressed to the families of the victims — four students and two teachers of Uwajima Fisheries High School in Ehime Prefecture and three crew members.