A Chinese ship collided into a Vietnamese cargo vessel, causing the Vietnamese ship to sink 120 miles off Vũng Tàu in the South China Sea.

The crash, between the Chinese Guo Shun 21 and the Vietnamese Thanh Dat 01 occurred on August 8. Two crew members, the captain and second engineer, are still missing, according to recent report. Nine other people, including a passenger, have been rescued.

The Thanh Dat 01 was en route from Vung Tau to Nghi Son, Gulf of Tonkin, Vietnam, loaded with 2718 tons of steel. The Vietnamese freighter was of 3,000+ dead weight tons flying the Vietnam flag.

China claims sovereignty in the heavily disputed South China Sea. A ruling by the an international court in the Hague last month dismissed China’s claims. Vietnam also has sovereignty claims in the area.

China has claimed the South China Sea is the “safest shipping route in the world,” but continues to reclaim land and militarize small islands in the sea in a bid to bolster its claims of sovereignty.

The Asia Maritime Transparency Initiative, a project of the Washington think tank Center for Strategic and International Studies (CSIS) has been reporting on Chinese civilian and military activities in the region. Just this week, an analysis of imagery released just this week showed civilian planes landing on Subi and Mischief reefs for the first time on July 12, giving China three operational runways in the disputed Spratly Islands.

The CSIS analysis expects Beijing to deploy military aircraft to these outposts in the near future, as indicated by the rapid construction of reinforced hangars at the three sites. “Each of the three islets will soon have hangar space for 24 fighter-jets plus three to four larger planes,” the report said.

The analysis shows that hangars constructed on Fiery Cross Reef and Subi Reef can accommodate fighter jet in the People’s Liberation Army Air Force, while construction on Mischief Reef is at an earlier stage. Construction continues at all three locations.

The U.S Navy conducts routine patrols through the international waters of the South China Sea. The amphibious dock landing ship USS Harpers Ferry completed such a patrol on August 4 and the Amphibious assault ship USS Boxer completed one on August 6. Both vessels are part of the Navy’s Boxer Amphibious Ready Group.