Former GOP presidential candidate Mitt Romney slammed former secretary of state (and likely 2016 Democratic presidential candidate) Hillary Clinton, calling her tenure atop the State Department a "monumental bust" during an interview Sunday on NBC's "Meet the Press."

Romney's comments, made from Utah, where he is hosting a summit of potential 2016 GOP candidates and donors, came as he criticized the Obama administration for failing to secure a "status of forces" agreement with the Baghdad government to keep a U.S. troop presence in Iraq after the December 2011 withdrawal.

The lack of such an agreement, Romney said, is partially to blame for the ongoing crisis in Iraq.

"Bad things happen as a result of inaction," Romney said. "The consequences have obviously been very severe."

He said that, in addition to Obama, Clinton is responsible for the ongoing turmoil in the Middle East.

"This administration, from Secretary Clinton to President Obama, has been repeatedly underestimating the threats that are faced by America. They have underestimated our adversaries," Romney said.

Moments later, he again attacked Clinton, saying that her time running the State Department was a "monumental bust" and that her statement in response to the trade of five Taliban members for U.S. soldier Bowe Bergdahl was "clueless."