The U.S. and Japan reportedly conducted a joint air exercise Saturday over the East China Sea amid heightened tensions in the region over North Korea's missile tests.

Japan's Air Self-Defense Force said that two Japanese F-15 fighter jets conducted the air exercise with two U.S. B1-B bombers, according to Reuters.

ADVERTISEMENT

The countries conducted a similar air exercise in late August south of the Korean peninsula, days after North Korea launched a ballistic missile over Japan.

South Korea was bracing for another possible missile test by North Korea on Saturday as Pyongyang marked its founding anniversary, which typically includes big displays of military hardware.

North Korea conducted its fifth nuclear test on the anniversary last year, while the isolated nation carried out its sixth nuclear test last weekend, prompting international condemnation.