U.S., U.K., and Japanese naval groups operated jointly in the Philippine Sea on Oct. 3, the U.S. Navy said on Friday.

The integrated at-sea operations had over 15,000 sailors cooperate across six countries. The Navy said this “demonstrates the U.S. Navy’s ability to work closely with its unmatched network of alliances and partnerships in support of a free and open Indo-Pacific.”

Participants included Carrier Strike Group (CSG) 5 with the USS Ronald Reagan (CVN-76), CSG 1 with the USS Carl Vinson (CVN-70), the U.K.’s carrier strike group (CSG 21) with the HMS Queen Elizabeth (R08) and the Japan Maritime Self Defense Force’s (JMSDF) Hyuga-class helicopter destroyer JS Ise (DDG 182).

The Navy noted CSG-5 is operating with CSG-1 for the first time in its 2021 deployment and the second time operating with the UK CSG-21 and JS Ise this year.

“We are picking up right where we left off in 5th Fleet with the Queen Elizabeth team and building on what we started with the JMSDF after first leaving Japan. Adding the fantastic Vinson team to this potent force dynamically displays our capabilities across all domains, keeping us ready to respond to a range of maritime challenges,” Rear Adm. Will Pennington, commander of Carrier Strike Group 5/Task Force 70, said in a statement.

The Navy said the naval forces conducted flight operations, air defense exercise scenarios and simulated strikes on maritime targets. Participating aircraft included the F/A-18E/F Super Hornets from Carrier Air Wing (CVW) 5 aboard the Ronald Reagan, F-35Bs from the Royal Air Force and U.S. Marines on the Queen Elizabeth and F-35Cs from CVW-2 from the Carl Vinson.

The U.S. Navy added this kind of training provides commanders with the opportunity to practice capabilities across the maritime domain like anti-air, anti-surface and anti-submarine warfare tactics and procedures.

“Interoperability across air platforms, to include the addition of the Air Wing of the Future, is just one way we have integrated operations for enhanced lethality, readiness and maneuverability across our collective forces,” Rear Adm. Dan Martin, commander of Carl Vinson Carrier Strike Group (VINCSG)/CSG 1, added.

The Vinson and U.K. carrier strike groups previously worked on joint interoperability flights n the 7th Fleet in August, the first time the U.S. carrier worked with F-35Cs. 

CSG-5 participants includes CVN-76 as well as the Ticonderoga-class guided-missile cruiser USS Shiloh (CG-67) and staffs from Task Force 70 and Destroyer Squadron (DESRON) 15. CSG-1 participants included CVN-70,  the Arleigh Burke-class guided-missile destroyers USS Chafee (DDG-90), USS Stockdale (DDG-106) and Ticonderoga-class USS Lake Champlain (CG-57).

Beyond the Queen Elizabeth, U.K. carrier group participants included the anti-submarine frigates HMS Richmond (F 239) and HMS Kent (F 78), guided-missile destroyers HMS Defender (D 36) and HMS Diamond (D 34), Royal Fleet Auxiliary’s RFA Fort Victoria and RFA Tidespring, U.S. destroyer USS The Sullivans (DDG-68), and Dutch frigate HNLMS Evertsen (F 805).

Japan’s contributions included JS Ise and destroyers JS Yamagiri (DD 152) and JS Kirishima (DDG 174).

The Royal Canadian Navy and Royal New Zealand navy also participated with the frigates HMCS Winnipeg (FFH 338) and HMNZS Te Kaha (F 77), respectively.

“Through this training, we enhanced our tactical skills and interoperability with the participating navies. In order to realize a Free and Open Indo-Pacific, the JMSDF will work closely with the naval forces of the U.S., Britain, the Netherlands, and Canada, which share the same objectives, to respond to global challenges and defend maritime order based on the rule of law,” Rear Adm. KONNO Yasushige, Commander of JMSDF Escort Flotilla 2, said.