Feb. 21 (UPI) -- The U.S. Navy's USNS Guadalupe replenishment oiler and the British Royal Navy frigate HMS Montrose conducted maritime security and logistics training this week during separate Chinese drills in the highly disputed South China Sea.
Participating in the exercise Monday were Royal Marine commandos, Royal Navy sailors and Guadalupe crew members, according to a U.S. Navy news release Wednesday.
China conducted 20 drills from Jan. 16 through Tuesday in the South China Sea as well as the western and central Pacific with its navy, air force and missile unit, according to a statement from the navy's South Sea Fleet obtained by South China Morning Post.
China, Vietnam, the Philippines, Taiwan, Malaysia and Brunei all claim overlapping territorial rights to the South China Sea, one of the world's busiest waterways.
Montrose's team boarded, searched and secured the Guadalupe, simulating a vessel engaged in high seas trafficking.
Despite not previously working together, the ships also safely and efficiently transferred fuel using NATO procedures.
"This was a valuable exercise for us, keeping our integrated Royal Navy and Royal Marines boarding team sharp and ready to deliver any mission assigned to them," said Cmdr. Conor O'Neill, commanding officer of HMS Montrose. "That we were able to achieve this training, and the replenishment drills afterwards, is testament to the close working relationship between the Royal and United States navies, both in the Pacific and globally."
Two other cooperative deployments in the South China Sea between the U.S. Navy and the Royal Navy have taken place since December. The USS McCampbell and HMS Argyll operated together in January, and a trilateral anti-submarine warfare exercise was held Dec. 21 and 22 between the U.S. Navy, Royal Navy and Japan Maritime Self Defense Force.
"It helps expand our capabilities and I believe it helps them, as well," said Eric Naranjo, civilian mariner chief mate aboard Guadalupe. "It's important because if you don't practice these scenarios, you won't have the skills necessary to succeed when the time comes."
Guadalupe, which is the 14th Henry J. Kaiser-class replenishment oiler, provides logistical support to U.S. Navy and allied forces operating in the U.S. 7th Fleet area of responsibility.
Chinese ships taking part in its drills were the guided missile destroyer Hefei, guided missile frigate Yuncheng, amphibious landing dock Changbaishan and the replenishment oiler Honghu.
The exercise had no pre-planned scenario and no advance notice to simulate a real wartime situation, according to a statement from the Chinese navy's South Sea Fleet
Training also included repelling advancing vessels, rescue by force and live-fire exercises.
Exercises were conducted on Woody Island, which is the largest of the contested Paracel Islands in the South China Sea. It is under China's control but also claimed by Taiwan and Vietnam.
Last week, two U.S. Navy guided-missile destroyers -- USS Spruance and USS Preble -- sailed within 12 nautical miles of a disputed artificial island, Mischief Reef, in the South China Sea, prompting "strong dissatisfaction" from China.
China and the United States are facing a March 1 deadline in which the United State has threatened to increase tariffs on $200 billion worth of Chinese imports.