Ashton Carter, President Obama's nominee for Defense secretary, said he has concerns about Iran's activities in Iraq, which could undermine U.S. efforts there against Islamic State in Iraq and Syria.
"I have concerns about the sectarian nature of Iran’s activities in Iraq," Carter wrote in answers provided to the Senate Armed Services Committee in advance of his confirmation hearing on Wednesday.
U.S. officials acknowledge that Iran has been supporting Shia militias in Iraq to fight ISIS, and recognize it as a positive development. But there are also reports that the Shia militias, with the cooperation of the Iraqi security forces, have targeted the country's Sunni minority.
The administration says defeating ISIS in Iraq will require Iraq's leaders to forge a government inclusive of its religious minorities.
"The U.S. has an interest in a stable, united, and inclusive Iraq with support from all of Iraq’s communities," Carter said.
The Obama administration says there is no cooperation or intelligence sharing between the U.S. and Iran in the fight against ISIS.
Some lawmakers have noted that Shia militias were responsible for violence against U.S. troops during the Iraq War, and remain dangerous.
Sen. John McCainJohn McCainMcCain: Nunes actions 'very disturbing' McCain calls North Korean leader a 'crazy, fat kid' McCain: Congress doesn't have 'credibility' to handle Russia probes MORE (R-Ariz.) said he learned while visiting Iraq in December that the "Shia militias are doing a lot of the fighting" there.
"They are the people we fought against during the surge," he said, referring to the U.S. troop increase in Iraq in 2007. "And they're Iranian-trained, and they're Iranian supplied. It's very, very dangerous."
This story was last updated on Feb. 4 at 12:21 a.m.