Pacific Air Forces flew B-52H Stratofortress bombers over the South China Sea Wednesday for the second time in a 9-day span as the United States keeps up its freedom of navigation and overflight campaign in the economically important region.

A pair of the bombers “took off from Andersen Air Force Base, Guam, and conducted routine training in the vicinity of the South China Sea March 13, 2019 (HST), before returning to base,” the Oahu-based command said in a statement. “U.S. aircraft regularly operate in the South China Sea in support of allies, partners, and a free and open Indo-Pacific.”

The command noted that U.S. bombers have flown from Guam for more than a decade as part of U.S. Indo-Pacific Command’s Continuous Bomber Presence mission in support of U.S. interests in the region.

The South China Sea fly-by came nine days after another B-52 mission to the area. Pacific Air Forces said two Stratofortresses took off from Guam on March 4 and participated in “routine training missions.”

“One bomber conducted training in the vicinity of the South China Sea before returning to Guam, while the other conducted training in the vicinity of Japan in coordination with the U.S. Navy and alongside our Japanese air force counterparts before returning to Guam,” the Air Force said.

China claims much of the South China Sea as its territory — an assertion the United States rejects.

The Navy’s 7th Fleet flagship USS Blue Ridge arrived in Manila Wednesday, meanwhile, for the ship’s first port visit to the Philippines in three years.

The Blue Ridge conducted a “cooperative deployment” with the Philippine Navy’s BRP Davao Del Sur before arriving, the Navy said.

“Our nations are longstanding allies and our navies have worked together for generations,” Vice Adm. Phil Sawyer, commander of 7th Fleet, said in a news release.

Sawyer said the visit “strengthens the bonds between our navies” and also noted the “shared commitment to a free and open Indo-Pacific.”