Staff members holds umbrellas to apparently hide the arrival of South Korea's National Intelligence Service Director Kim Kyou-hyun at Dulles International Airport on the outskirts of Washington, July 19. Yonhap

South Korea's National Intelligence Service (NIS) Director Kim Kyou-hyun has made an unannounced visit to the United States amid concerns over the possibility of North Korea conducting a nuclear test or other provocative acts.

Kim was spotted walking out of Dulles International Airport on the outskirts of Washington, D.C., on Tuesday morning (Washington time) as his staff members held large umbrellas apparently to conceal the movement of the country's top intelligence official.

His visit came as Seoul and Washington have been cranking up security coordination amid speculation Pyongyang could further ratchet up tensions by carrying out what would be its seventh nuclear test.

His detailed schedule remains unknown, but he is expected to meet top U.S. intelligence officials like Avril Haines, director of national intelligence, and William Burns, director of the Central Intelligence Agency.

The NIS refused to confirm Kim's visit to the U.S.

"Our principle is not to confirm where the intelligence agency chief is," an NIS official told Yonhap News Agency over the phone, requesting anonymity.

While in the U.S. capital, Kim is expected to focus on reinforcing deterrence against a provocative North Korea.

North Korean leader Kim Jong-un reaffirmed his regime's principle of "power for power and head-on contest" during last month's key ruling party session ― a move that stoked concerns about Pyongyang's future provocations. (Yonhap)