FILE - One of two U.S. Air Force B-1B Lancer bombers is refueled during a 10-hour mission flying to the vicinity of Kyushu, Japan, the East China Sea, and the Korean peninsula, over the Pacific Ocean, Aug. 8, 2017.
FILE - One of two U.S. Air Force B-1B Lancer bombers is refueled during a 10-hour mission flying to the vicinity of Kyushu, Japan, the East China Sea, and the Korean peninsula, over the Pacific Ocean, Aug. 8, 2017.

The United States again flew bombers over the disputed South China Sea this week, U.S. officials disclosed Wednesday, a move likely to intensify the already fraught tension between Beijing and Washington. This is at least the second time this month the U.S. has flown bombers over the area.

China has long claimed ownership of a vast swath of the South China Sea, an important international trade route through which billions of dollars worth of cargo is shipped annually, and it holds potentially billions of dollars worth more in untapped mineral resources.

The area China claims stretches far below its southern coast, hugging and sometimes overlapping the shorelines of Taiwan, Vietnam, Malaysia, Brunei and the Philippines, all of whom have made their own, smaller, claims in the region.

China argues it has had sovereignty over the area going back hundreds of years, first issuing a map showing the area as a part of their country in the 1940s. The nation has spent years trying to protect its claim by building military installations on artificially created islands, replete with naval vessels, nuclear bombers, and fighter jets. 

The U.S. regularly tries to undermine China by sending ships and planes into the region on “freedom of navigation” missions, displays of defiant disregard for the claim.

The move comes at at a tense time — China and the U.S. currently are embroiled in a trade war, and U.S. President Donald Trump accused China Wednesday of trying to meddle in U.S. elections.