A US Army Apache helicopter went down on Monday in the central South Korea during training, leaving two pilots dead.
The cause of the crash near Wonju in Gangwon province, was not clear.
Two bodies received from the helicopter were badly damaged and officials couldn't immediately ratify their identities, the officer said.
Captain Jeff Davis, a Pentagon spokesman said "This happened during a routine training mission and sadly did kill both pilots."
"The cause is currently under investigation," he added.
The identities of the pilots have been kept until their families have been notified.
"We offer our heartfelt prayers and condolences to the families of the soldiers involved in this tragic incident," Lt. Col. Mark Gillespie, deputy commander of 2nd Combat Aviation Brigade, said in a US Army statement.
Nearly 28.500 US troops are positioned in South Korea in order to back up South Korea’s forces against North Korea.
According to military officials on Monday, South Korea conducted live firing exercise close to the debated inter-Korean sea border although North Korea’s caution of “merciless” retribution.
South’s defence ministry said that military exercise was conducted front-line islands in the Yellow Sea to commemorate the anniversary of North Korea’s deadly bombing of one of the islands 5 years ago.