Washington ? The Obama administration on Wednesday slapped new sanctions on several affiliates of Iran’s Revolutionary Guard Corps amid stepped-up efforts to get U.N. penalties against Tehran because of its nuclear and missile programs.

The Treasury Department said it was freezing the assets in U.S. jurisdictions of Revolutionary Guard Gen. Rostam Qasemi and four subsidiaries of a previously penalized construction firm that he runs over their alleged involvement in producing and spreading weapons of mass destruction.

The sanctions made public Wednesday expand existing U.S. unilateral penalties against elements of the Guard Corps, or IRGC, which Western intelligence officials believe is spearheading Iran’s nuclear program. The step is in line with statements from administration officials that they want sanctions to target Iranian elites responsible for such activity and not the Iranian people in the hope of changing the government’s behavior.