WASHINGTON/SEOUL (Reuters) - The U.S. Department of Energy has designated ally South Korea a "sensitive" country, a spokesperson said on Friday, after the South Korean president briefly imposed martial law and amid talk of Seoul potentially developing nuclear weapons.

Acting President Choi Sang-mok on Monday instructed the government to engage with the United States to prevent any adverse impact on energy cooperation following Washington's designation of South Korea as a "sensitive" country.

The U.S. Department of Energy (DOE) has designated South Korea as a sensitive country, a move linked to concerns over nuclear proliferation and recent political turmoil in Seoul. The classification, made in January