By Timothy Gardner, David Brunnstrom and Ju-min Park 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.

South Korea's foreign minister told the country's legislature Wednesday that developing nuclear weapons is not off the table

The U.S. Department of Energy has categorized South Korea as a 'sensitive' country, amid tensions over nuclear proliferation concerns. The designation may affect U.S.-ROK cooperation in science and technology.

Several South Korean leaders have said Seoul may pursue nuclear weapons amid fears over Pyongyang’s weapons programme.