A South Korean navy Lynx helicopter takes part in exercises in the undated photo. A search was underway Tuesday, Sept. 27, 2016, for three crew members missing after a Lynx crashed into the sea off the country's east coast while participating in joint maritime drills with the U.S. Navy.

SEOUL, South Korea — A search was underway Tuesday for three crew members missing after a South Korean military helicopter crashed into the sea off the country’s east coast while participating in joint maritime drills with the U.S. Navy.

The Lynx helicopter sent out a distress signal and disappeared from radar eight minutes after taking off from an Aegis destroyer Monday evening.

So far, searchers have found only debris, including the helicopter’s door and a helmet, a South Korean military official said, speaking on condition of anonymity according to department policy.

The crash site was near the inter-Korean maritime border known as the Northern Limit Line, but the official said currents suggested any drift would have been in a different direction.

An investigation into the cause of the crash was ongoing, but weather conditions were not a problem, another official said.

Pyongyang does not acknowledge the NLL, saying it was unilaterally drawn by the U.S.-led United Nations Command after the 1950-53 war on the peninsula ended in an armistice instead of a peace treaty.

All 20 Lynx helicopters operated by the South’s navy will be suspended pending an investigation into what caused the accident, the Yonhap news agency reported. The helicopter that crashed is more than 30 years old and was first deployed to the navy in 1999, it said.

The joint navy drills involved guided-missile destroyers, including the USS Spruance, submarines and helicopters in a display of military might against a growing threat from North Korea, which has conducted two nuclear tests and several missile launches this year.

gamel.kim@stripes.com

Twitter: @kimgamel

