American B-1B strategic bombers join South Korean fighter jets for drills against North Korean threats.
In a move expected to anger North Korea, the bombers took part in firing drills with South Korean F-15K fighter jets over waters to the east and west of the peninsula.
Seoul's Joint Chiefs of Staff revealed Wednesday morning the bombers entered Korean air space before 9 p.m. after flying over from their base in Guam and did not leave until about 11.30 p.m.
"South Korean and U.S. air forces showed off the allies' resolve for strong retaliation against North Korea's nuclear and missile threats," the JCS said in a statement carried by local news agency Yonhap.
North Korea warned last month it could shoot down U.S. bombers at its discretion amid heightened tensions in the wake of Pyongyang's sixth ever nuclear test.
Seoul and Washington have been on alert over a possible North Korean long-range missile test in line with this week's anniversary of the founding of the reclusive state's ruling party.