Two US B-52 strategic bombers flew over the East Sea last week, an aviation tracker said, in a mission possibly designed to send a warning in response to North Korea's recent series of missile launches.
The bombers, which took off from Guam's Anderson Air Base, "conducted a mission" in the East Sea and "possibly the South China Sea" on Friday, Aircraft Spots said on a Twitter post. Three KC-135R aerial tankers provided support for their flight.
The B-52 is considered a representative strategic asset of the United States, along with intercontinental ballistic missiles and ballistic missile submarines.
This captured image from US Air Force's homepage shows B-52 strategic bombers (Yonhap)
The plane had not appeared often near the Korean Peninsula since North Korea began its full-fledged diplomatic push with South Korea and the US early last year.
The latest flight came after the North conducted a series of short-range ballistic missile tests in recent months and test-fired a new submarine-launched ballistic missile early this month.
The US and North Korea held working-level nuclear talks in Stockholm in early October after months of stalemate, but the talks broke down again, with Pyongyang accusing Washington of failing to come up with a new proposal.
Some observers say the latest US mission appears aimed at keeping China and Russia in check.
In July, Chinese and Russian aircraft entered South Korea's air defense identification zone, an area of the skies declared by a state for the early identification and location of foreign planes approaching its territorial airspace.
Last week, six Russian military planes breached the KADIZ over the East Sea a further four times. (Yonhap)