What the July 10 Western Pacific pulse means for RAF allies
On July 10, 2026, USNI News reported that RIMPAC 2026 entered its at-sea phase while RAF-linked allied air forces opened Exercise Southern Cross 26 with U.S. and Japanese F-35s at Australian bases. The same week, USS Charlotte—the submarine that sank Iran's IRIS Dena—joined Pacific drills as the Navy tested a new undersea hunter-killer concept.
Key Takeaways
- RIMPAC 2026 shifted to at-sea operations on July 10, with ships and unmanned surface vessels departing Pearl Harbor in stages Monday through Thursday.
- RAF-linked Royal Australian Air Force bases hosted the inaugural Southern Cross 26 F-35 integration drill through July 17.
- USS Charlotte, which torpedoed IRIS Dena in March, is one of five submarines at RIMPAC amid scrutiny over 20 unrecovered crew remains.
- China and Russia began the sea phase of Joint Sea 2026 in the Yellow Sea off Qingdao.
- COMSUBPAC is pairing UUVs with Harpoon missile strikes in a distributed hunter-killer demonstration.
What did the July 10 Western Pacific pulse report?
USNI News' Western Pacific Pulse for July 10, 2026, is a weekly roundup of major ship movements and exercises across the region. The headline development was RIMPAC's transition from harbor activities to open-ocean training, with ships and unmanned surface vessels leaving Joint Base Pearl Harbor–Hickam in stages from Monday through Thursday.
Separately, the USS George Washington Carrier Strike Group remained in the Philippine Sea after completing Exercise Valiant Shield on July 1. The carrier conducted a fueling-at-sea evolution with fleet oiler USNS Earl Warren and held a frocking ceremony on Friday, according to USNI News.
Why is USS Charlotte drawing scrutiny at RIMPAC 2026?
One of five submarines participating in RIMPAC is USS Charlotte, which Common Dreams identified as the U.S. Navy's so-called killer submarine. On March 4, 2026—five days after the U.S.-Israel war on Iran began—the boat torpedoed Iranian frigate IRIS Dena in international waters 19 nautical miles off Sri Lanka.
Of the 136 personnel aboard Dena, only 32 survived and reports indicate the remains of 20 deceased sailors were never recovered. It is the only instance since World War II in which a U.S. Navy submarine sank a surface vessel using torpedoes. Cases involving missing remains at sea often draw sustained public interest, similar to other maritime mysteries covered in our True Crime & Unsolved Mysteries archive.
What is Exercise Southern Cross 26?
The U.S. Air Force, Royal Australian Air Force and Japan Air Self-Defense Force began the inaugural Exercise Southern Cross 26 on Monday, running until July 17 at RAAF bases Darwin and Tindal. The drill focuses on large-force integration of F-35 Lightning II fighters from all three countries.
Japan deployed six F-35As from the 3rd Air Wing, two E-2D Hawkeye airborne early-warning aircraft and one KC-46A Pegasus tanker. The RAF-linked Australian bases sit thousands of miles from Hawaii, showing how allied air power is being exercised on two Pacific fronts simultaneously.
How is the Navy's hunter-killer concept changing undersea warfare?
Army Recognition reported that during RIMPAC 2026, Commander, Submarine Force, U.S. Pacific Fleet is demonstrating a distributed hunter-killer network. Autonomous unmanned underwater vehicles extend undersea intelligence and surveillance into denied areas, then relay targeting data through secure networks to submarines armed with UGM-84 Harpoon anti-ship missiles.
U.S. 3rd Fleet announced the activities on July 3, 2026. The concept compresses the sensor-to-shooter timeline while keeping crewed submarines outside an enemy's immediate anti-submarine screen—an approach framed as a response to China's expanding naval presence in the Indo-Pacific.
What else is happening in the Western Pacific?
Chinese and Russian naval ships and submarines departed Qingdao on Thursday to begin the sea phase of Joint Sea 2026, also called Maritime Interaction 2026. Drills in the Yellow Sea include joint rescue operations, anti-submarine warfare, air defense and live-fire training through July 13, after which some assets are expected to conduct joint patrols.