The U.S. has sent B-52 bombers near disputed islands in the South China Sea, the U.S. Pacific Air Forces said Thursday, the second such mission over the contested waterway in 10 days.

The Pacific Air Forces (PACAF) said in a statement that the two B-52s had taken off from Andersen Air Force Base on the U.S. island territory of Guam, and participated in "routine training missions."

"U.S. aircraft regularly operate in the South China Sea in support of allies, partners, and a free and open Indo-Pacific," the statement said.