Bob Werner was previously the head of the US Treasury's Office of Foreign Assets Control (OFAC) - the agency responsible for enforcing the US sanctions on countries including Iran.
"It's been very good to get beyond this finger pointing, and the U.S. saying, 'You should keep those horrible drugs out of the hands of all of our above-average children, ' " said Gil Kerlikowske, head of the White House Office on National Drug Control Policy.