WASHINGTON, Nov 5 (Reuters) - A U.S. Army soldier who was in critical condition after suffering non-combat injuries while supporting the military's pier off the coast of Gaza has died, the U.S. military said on Monday.

Sergeant Quandarius Davon Stanley, who recently retired from the military, suffered critical injuries in May while supporting operations at sea of the U.S.-built pier designed to increase flows of humanitarian aid into the Gaza Strip.

In a statement, the U.S. Army confirmed that Stanley had died, though it did not specify when. He was receiving treatment in a long-term care medical center.

"Stanley was an instrumental and well respected first line leader in the 7th Transportation Brigade Expeditionary $(TBX)$, especially during the mission to provide humanitarian assistance to the people of Gaza," Colonel John "Eddie" Gray, commander of the unit, said.

Three U.S. troops were injured during the pier operation, but the other two were minor injuries and have returned to duty.

The U.S. military ended its pier operation in July, months after Biden announced plans to put the pier in place for aid deliveries as famine loomed in Gaza, an enclave of 2.3 million people.

It involved 1,000 U.S. troops, delivered only a fraction of the promised aid at a cost of nearly $230 million, and was from the start beset by bad luck and miscalculations, including fire, bad weather and dangers on shore from the fighting between Israel and Hamas.

The U.S. military has said the mission was a success, delivering the largest amount of aid ever into the Middle East.

More than 43,300 Palestinians have been killed in more than a year of war in Gaza, according to Gaza authorities, and much of the territory has been reduced to ruins.

The war erupted after Hamas-led militants attacked Israel on Oct. 7, 2023, killing some 1,200 people and taking 251 hostages back to Gaza, according to Israeli tallies.

(Reporting by Idrees Ali and Phil Stewart; Editing by Himani Sarkar)

((Idrees.Ali@thomsonreuters.com; 301-747-8263;))