U.S. Navy Sinks Two Decommissioned Warships in RIMPAC 2026 Exercise Off Hawaii
When the sun set over the Pacific, the U.S. Navy turned two retired giants into training targets. During the Rim of the Pacific 2026 (RIMPAC 2026) exercise, the Navy carried out two sinking exercises (SINKEXs) that saw the decommissioned cruiser USS Mobile Bay (CG‑53) go down on July 11 and the amphibious assault ship USS Peleliu (LHA‑5) on July 17. Both ships were scuttled in waters 15,000 feet deep, more than 50 nautical miles off the northern coast of Kauai, as part of a series of live‑fire drills that tested the capabilities of U.S. forces and a broad coalition of partner navies.
Mobile Bay, a Ticonderoga‑class guided‑missile cruiser that first steamed into service in February 1987, had spent 36 years on the front lines before being decommissioned in August 2023. Peleliu, a Tarawa‑class amphibious assault ship that entered service in May 1980, was retired in March 2015 after 35 years of duty. The Navy chose these vessels for the SINKEXs because they had been out of commission for several years and were ready for disposal.
The two sinkings were carried out under the auspices of Combined Task Force (CCTF) and Combined Force Maritime Component Command (CFMCC) for RIMPAC 2026, a biennial exercise hosted by the U.S. Indo‑Pacific Command at Pearl Harbor. The exercise, which began on June 24 and runs through July 31, has already drawn more than 30 surface ships, five submarines, over 200 aircraft and a wide range of partner nations.
On July 11, as Mobile Bay slipped beneath the waves, forces from Australia, Canada, Italy, Japan, New Zealand and Spain joined U.S. Navy, Air Force and Army units in a coordinated barrage. A U.S. Navy F‑18 Super Hornet launched an AGM‑158C Long‑Range Anti‑Ship Missile from a Hawaiian air base, while the 1st Battalion, 623rd Field Artillery of the Kentucky National Guard fired a High Mobility Artillery Rocket System (HIMARS). Japan’s Ground Self‑Defense Force 8th Surface‑to‑Surface Missile Regiment launched Type 12 surface‑to‑surface missiles, and U.S. Army AH‑64 Apache attack helicopters fired Spike Non‑Line‑of‑Sight missiles. A periscope shot captured Mobile Bay’s final moments as it sank.
The joint live‑fire also highlighted the ability of ground‑based artillery and Japanese missile units to engage a naval target from a distance. According to a U.S. Army news release, the 1‑623 FA and the JGSDF’s 8th SSMR conducted a combined barrage on the cruiser on July 11.
Six days later, on July 17, Peleliu met a similar fate. After being towed out to sea in April 2026 to simulate battle damage, the ship was moved to the sinking area. Partner navies again took part: the Royal Australian Navy’s destroyer HMAS Sydney, armed with the Naval Strike Missile, fired an AGM‑114N Hellfire missile; the Spanish frigate ESPS Álvaro de Bazán launched a Harpoon missile; the Japanese destroyer JS Kongo also fired a Harpoon; the New Zealand frigate HMNZS Te Mana’s SH‑2G helicopter fired a Penguin anti‑ship missile; and the Italian multi‑role vessel ITS Giovanni delle Bande Nere’s SH‑101 helicopter launched a Marte missile.
The U.S. submarine USS Columbia (SSN‑771) also played a role. On July 10, RIMPAC’s official social media account posted photos of Columbia loading a UGM‑84 Harpoon anti‑ship missile in preparation for a SINKEX. A June U.S. Navy news release noted that Columbia and the attack submarine USS Charlotte (SSN‑766) would conduct precision long‑range fires during RIMPAC 2026 using Harpoon missiles.
Vice Admiral Jeff Jablon, commander of the RIMPAC 2026 Combined Task Force, said the exercises highlighted the strength and readiness of U.S. partnerships. Rear Admiral Inho Kim of the Republic of Korea Navy echoed that the SINKEXs demonstrated a shared commitment to regional stability.
Sinking Mobile Bay and Peleliu provided a realistic training environment for naval and joint forces, allowing crews to practice targeting, weapons deployment and damage assessment against actual ship hulls. It also served as a method of disposing of decommissioned vessels in a controlled, environmentally responsible manner.
As RIMPAC 2026 continues through July 31, participating nations will conduct additional live‑fire drills and maritime operations. The SINKEXs on July 11 and 17 have already demonstrated the effectiveness of combined U.S. and partner forces in executing complex maritime events. The exercise will conclude with a debriefing of lessons learned and a review of performance metrics, ensuring that the participating navies can refine tactics and improve interoperability for future operations.
