The Pakistani scientist has been accused of supplying equipment and designs to help get nuclear programs off the ground in Iran, Libya and North Korea.

The U.S. State Department said in a written statement it took an international effort to put Khan and his ring out of business but not before it had "irrevocably changed the proliferation landscape" and brought about lasting security implications.

The sanctions were imposed under the Nuclear Proliferation Act, Export-Import Bank Act and Executive Orders 12938 and 13382.

"We believe these sanctions will help prevent future proliferation-related activities by these private entities, provide a warning to other would-be proliferators, and demonstrate our ongoing commitment to using all available tools to address proliferation-related activities," the State Department said.