The U.S. Air Force has sent a B-52 bomber over the East China Sea and Sea of Japan for a large-scale training mission involving 16 Air Self-Defense Force fighter jets, both countries' militaries said Friday.

The mission, which took place a day earlier, was the latest display by the U.S. and Japanese militaries of their improving integrated operations.

In a statement, Japan's Defense Ministry said the training was conducted to improve the two allies' tactical skills. The U.S. Pacific Air Forces, meanwhile, characterized the drill as "a routine training mission."