SAN DIEGO — Navy Secretary Carlos Del Toro issued letters of censure to the five military commanders Marine and Navy investigations found to bear some responsibility for the conditions that contributed to the July 2020 fatal sinking of an assault amphibious vehicle off the San Diego coast. Eight Marines and a sailor were killed when their AAV broke down and sank during training with the 15th Marine Expeditionary Unit while returning to the amphibious transport dock Somerset from San Clemente Island. Those censured include retired Marine Lt. Gen. Joseph Osterman, who was the three-star general …