SEOUL // A US military helicopter taking part in a joint South Korea-US drill crashed today near the North Korean border, officials said.
A US military official identified the aircraft as a CH-53 US Marine helicopter that was carrying three crew and 13 other personnel during a training exercise.
No casualties were reported.
The Yonhap news agency had previously identified the helicopter as a UH-60 Black Hawk with 12 personnel on board.
The US official described the crash as a "hard landing" in Cheolwon county, which touches on the border with North Korea.
The Korean peninsula is currently at a state of heightened military tensions, partly due to North Korea's anger over the ongoing South Korea-US military exercises, which it sees as an invasion rehearsal.
There are 28,500 US military personnel permanently stationed in South Korea.
Meanwhile North Korea's military threatened the South with imminent "sledge-hammer" retaliation unless Seoul apologised for anti-Pyongyang protestors burning effigies of its revered leaders.
South Korea called the North's ultimatum "regrettable" and "absurd" with the defence ministry vowing a tough response to any military provocation.
The warning came a day after US Secretary of State John Kerry wrapped up a Northeast Asian tour aimed at defusing soaring military tensions on the Korean peninsula and getting China to help rein in a belligerent Pyongyang.