The U.S. Air Force has sent two B-52 bombers over the East China Sea for "routine training" near Okinawa Prefecture, the military has said, the latest mission in the waterway that is home to the Japanese-controlled Senkaku Islands.

The B-52 bomber mission was part of so-called continuous bomber presence operations by the U.S., which the military says "have been ongoing since March 2004" and "are consistent with international law and United States' long-standing and well-known freedom of navigation policies."

The exercise also came just ahead of high-level U.S.-China talks scheduled for Wednesday in Washington aimed at finding a solution to a trade war that has cast a growing shadow over the world's top two economies.