South Korea’s navy rescued a North Korean soldier found in the waters off the west coast and authorities were questioning him over whether he had been spying, an official said on Monday.

South Korea will decide how to handle the matter after the investigation, an official at the National Intelligence Service said. He spoke on condition of anonymity because the investigation is under way.

The official didn’t provide further details, but South Korea’s Yonhap news agency reported that the soldier ended up in South Korean waters Sunday while fishing. Yonhap said he had asked to be sent back to the isolated North.

The two Koreas technically remain in a state of war because their 1950-53 conflict ended in a truce. Their navies engaged in a brief but deadly gunbattle several weeks ago off the west coast.

North and South are divided by a heavily fortified land border, but North Korea disputes the western maritime border drawn by the United Nations decades ago.

The western waters, a prized fishing spot for both Koreas, have been the site of three bloody naval clashes in the past decade. One North Korean officer was killed and three others wounded in the latest gunfight, according to the South Korean military.

Tensions on the Korean peninsula have been high this year, with North Korea carrying out nuclear and missile tests.

However, impoverished, isolated North Korea has reached out recently to Seoul and Washington. President Barack Obama is to send a special envoy to Pyongyang next week to try to entice the North to return to international nuclear disarmament talks.

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