On Friday Colin Kahl was named Vice President Joe Biden’s national security adviser and deputy assistant to the president. Kahl previously served in the Obama administration as deputy assistant secretary of defense for the Middle East between 2009-2011, but is probably best known for his work outside of government—in particular, for advocating containment of a nuclear Iran, and for his part in trying to remove the recognition of Jerusalem as capital of Israel from the 2012 Democratic platform.

In his role as senior fellow at the Center for a New American Security, a think tank close to the Obama administration, Kahl floated what was widely recognized as a trial balloon on behalf of the administration when he co-authored a report explaining how American policymakers would go about containing a nuclear Iran. Kahl’s report, “If All Else Fails: The Challenges of Containing a Nuclear-Armed Iran,” argued that while Obama says his policy is to prevent Iran from getting the bomb, the fact is that “prevention – up to and including the use of force – could fail, leaving Washington with little choice but to manage and mitigate the consequences of a nuclear-armed Iran.”