The international community had failed to protect Iranian opposition members in Camp Liberty, Iraq, whose safety and future freedom must now be insured, US General George W Casey told a conference in Arizona.
The leader of US troops in Iraq from 2004 to 2007 also said in a speech in conference entitled Countering Iran's Nuclear, Terrorist Threats: "The Iranian regime has and will continue to use terrorism to accomplish their political objectives."
General George Casey said of the members of the People's Mojahedin Organization of Iran (PMOI/MEK) in Camps Ashraf and Liberty: "I watch with dismay in 2009 and 2011 and in 2013 as the men and women that we vowed to protect were savagely attacked. After the United Nations, after the Iraqi government, and after the US government had agreed that the MEK must be protected and resettled. We must ensure the protection of the MEK as long as they are in Iraq and until they're resettled."
The Iranian regime trained and equipped Iraqi militia from 2006 to 2008 and as a result was responsible for the deaths of hundreds of coalition forces and thousands of Iraqis, General George Casey said.
He added: "They richly deserve the label of state sponsor of terrorism that they have so well earned.
"We can count on this regime to continue to foster regional instability. Iran with nuclear weapons would present an unacceptable not only for the region but to the entire international community. And I can think of no other case in which organized democratic resistance against a regime is so warranted and so necessary."
He said the Iranian regime is fostering instability through the training and equipping of terrorist organizations.
He added: "By the middle of 2006 there was no doubt that the Iranian regime was training an army, Iraqi militia and terrorist organization.
"Later in 2006 we began to see a very troubling trend, and it appeared to us that Iraqi militia backed by the Iranians were actively pushing other Iraqis out of parts of Baghdad to expand their control over parts of the city.
"Our Special Operations forces captured six Quds Force operatives in what amounted to a command center with the Shia militia group the Badr corps. And the Badr corps was the militia of one of the major Shia political parties.
"It was immediately clear to me that the Iranian regime was directly and purposefully fomenting sectarian violence to destabilize Iraq."