Sullivan & Cromwell has hired Adam Szubin, a former top official at the U.S. Department of the Treasury, where he was a key architect of the Obama administration's controversial nuclear deal with Iran. Szubin will join the firm's financial services group as of counsel in Washington, D.C.

“Sullivan & Cromwell's unparalleled reputation, deep expertise, and international reach will enable me to add significant value for the firm's clients in the U.S. and around the world,” Szubin said in a statement Monday. “I am thrilled to be joining their highly talented team.”

Szubin, a career civil servant, has spent the last 13 years at the Treasury Department where he led the agency's policy and enforcement efforts targeting the financial support veins of international terrorist organizations, narcotics traffickers and other threats to U.S. national security.