The U.S. Department of Energy has imposed restrictions on China's imports of civil nuclear technology to prevent its use for military or other unauthorized purposes, Reuters reported.

The new policy is effective immediately, according to U.S. officials, and sets guidelines for the review of all existing and future technology transfers into China. Most of the existing technology transfers approved before Jan. 1 are likely to remain unchanged, the report said. Officials expressed concern over the development of nuclear technology to power small reactors in the South China Sea and its use in weapons.

The move came a day after the U.S. Justice Department said it had arrested and indicted an alleged spy for China's Ministry of State Security on charges of trying to steal trade secrets from U.S. aviation and aerospace companies.

In 2017, the National Security Council initiated a review of China's efforts to obtain nuclear material, equipment and technology from U.S. companies, according to government officials. U.S. nuclear exports to China amounted to $170 million in 2017, the officials reportedly said.