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David Petraeus: Biggest threat to Iraq's future is Iran, not ISIS

David Petraeus speaks onstage during a fireside chat at the Team Rubicon Salute To Service Awards at Skirball Cultural Center on November 7, 2014 in Los Angeles, California.

Imeh Akpanudosen, Getty Images

The greatest threat to long-term stability in Iraq is not Sunni militants with the Islamic State of Iraq and Syria (ISIS), but rather the Iranian-backed Shiite militias who have helped oust ISIS from parts of the country, General David Petraeus warned in an interview published Friday by the Washington Post.

Petraeus, who commanded U.S. troops during the height of America's war in Iraq, said the current situation there is "hard but not hopeless." He warned, though, that the Iranians will not play a constructive role in Iraq's future, despite the fact that the U.S. and Iran share a common foe in ISIS.

"I would argue that the foremost threat to Iraq's long-term stability and the broader regional equilibrium is not the Islamic State; rather, it is Shiite militias, many backed by -- and some guided by -- Iran," he said.

"They prevented the Islamic State from continuing its offensive into Baghdad," he acknowledged. "Nonetheless, they have, in some cases, cleared not only Sunni extremists but also Sunni civilians and committed atrocities against them. Thus, they have, to a degree, been both part of Iraq's salvation but also the most serious threat to the all-important effort of once again getting the Sunni Arab population in Iraq to feel that it has a stake in the success of Iraq rather than a stake in its failure."

Left unchecked, the Shia militias could "emerge as the preeminent power" in Iraq, he said, "outside the control of the government and instead answerable to Tehran."

"The current Iranian regime is not our ally in the Middle East," Petraeus explained. "It is ultimately part of the problem, not the solution. The more the Iranians are seen to be dominating the region, the more it is going to inflame Sunni radicalism and fuel the rise of groups like the Islamic State. While the U.S. and Iran may have convergent interests in the defeat of [ISIS], our interests generally diverge."

Petraeus also suggested he's worried about the ongoing conflict in Syria, which he described as a "geopolitical Chernobyl."

"Until it is capped, it is going to continue to spew radioactive instability and extremist ideology over the entire region," he said, suggesting that any lasting solution to the conflict in the region must bring tensions under control in both Syria and Iraq.

Petraeus has recently been in the news due to some legal troubles. He was accused earlier this year of giving classified materials to Paula Broadwell, his mistress and biographer, while he was the director of the CIA. Earlier this month that he entered an agreement to plead guilty to a single count of mishandling classified materials. He will be sentenced on April 23. In spite of his legal woes, Petraeus is still advising the White House on security issues in Iraq, White House Press Secretary Josh Earnest confirmed Monday.