The US Department of Defense has announced that a US B-52 bomber was flown over Osan province in South Korea.
The flight follows the recent nuclear test by North Korea.
The strategic bomber was joined by US F-16 fighter aircraft and South Korean F-15 fighter aircraft.
Pacom commander Admiral Harry B. Harris Jr., said: "This was a demonstration of the ironclad US commitment to our allies in South Korea, in Japan, and to the defence of the American homeland.
"North Korea's nuclear test is a blatant violation of its international obligations.
"US joint military forces in the Indo-Asia-Pacific will continue to work with all of our regional allies and partners to maintain stability and security."
A US Pacific Command news release stated: "The bilateral flight mission demonstrates the strength of the alliance between the United States and the Republic of Korea and the resolve of both nations to maintain stability and security on the Korean Peninsula."
The B-52 returned to Guam upon completion of the flight over South Korea.
Manufactured by Boeing, the B-52 Stratofortress is a long-range, subsonic, strategic bomber designed to carry and fire both nuclear and conventional munitions for deterrence missions.
Last week, North Korea successfully tested a hydrogen bomb, bolstering the country's nuclear strike capabilities.
North Korea had also conducted an ejection test of its new Bukkeukseong-1 (Polaris-1, KN-11) submarine-launched ballistic missile (SLBM) as a part of its SLBM development programme, at the Sinpo South Shipyard.