China and the Philippines are fighting over a sunken World War II-era ship

The Republic of the Philippines’ Navy ship BRP Sierra Madre has a long history, and though it was originally built in 1944, it still serves a very important strategic purpose for the Philippines: Keeping China away from its territorial waters.

BRP Sierra Madre actually began its life as an American tank landing craft during World War II. Constructed in Indiana by the Missouri Valley Bridge & Iron Company, it was originally christened the USS Harnett County. The Harnett County served with the United States through World War II and participated in landings at Eniwetok, Okinawa and Guam.

It was recommissioned in 1966 and sent to service in the Vietnam War, where it was used as a floating helicopter base in the Mekong River Delta. After two wars, nine battle stars and three Navy Unit Commendations, it was transferred to the Republic of South Vietnam. Renamed the RVNS My Tho, the ship served in the South Vietnamese Navy until Saigon fell to North Vietnam in 1975.

Refugees packed the ship after the fall of South Vietnam’s capital. It met up with other fleeing South Vietnamese ships until they formed a flotilla at sea and sailed for the Philippines’ Subic Bay. The Philippines then took possession of My Tho and other former South Vietnamese ships in the bay. Through the 1990s, the Philippines operated the ship as the BRP Sierra Madre, using it as an amphibious transport.

Then, in 1999, the Philippine Navy ran Sierra Madre aground on the Second Thomas Shoal, an atoll in the Spratly Islands of the South China Sea. The Philippines wanted the ship and its complement of Marines there to back up its territorial claim to the islands. Ever since, a detachment of Filipino Marines has maintained a force aboard the ship. As China began pressing its own claims to the islands, the two nations have sparred over the tiny atoll and the Sierra Madre.

In 2014, the Chinese coast guard began harassing ships bound to resupply the Sierra Madre and its contingent of Marines. A de facto blockade was set up, and the Philippines had to either evade the blockading ships or resupply its Marines by air. Chinese efforts to disrupt the Sierra Madre’s mission have only intensified since.

In February 2023, the Chinese Coast Guard began using military lasers to blind the Filipino crew. In August of 2023, the Chinese began firing water cannons at Philippines Coast Guard ships on resupply missions. In response, Philippines President Bongbong Marcos expanded the Enhanced Defense Cooperation Agreement, the island nation’s defense agreement with the United States.

That hasn’t dissuaded any Chinese aggression. In September 2023, the Chinese coast guard and ships from China’s maritime militia attempted to block Philippine resupply missions to Sierra Madre on two separate occasions. Manila is considering building hardened facilities on the shoal, which is also known as Ayungin Shoal. It would be a significant escalation of its territorial claim, especially as China has become increasingly aggressive against foreign ships in the Spratly Islands.

The Philippines is not the only country contending for ownership of the islands, either. Taiwan, Malaysia, Vietnam, and Brunei all claim ownership of the chain, and Brunei is the only country that doesn’t occupy one or more of the islands’ many landmasses, shoals, and atolls.