Iran's direct support for an Iraqi push to dislodge the Islamic State group from the northern city of Tikrit could turn out to be "a positive thing" if it does not inflame sectarian tensions, the top U.S. general said Tuesday.
The statement by Gen. Martin Dempsey, chairman of the Joint Chiefs of Staff, reflected the delicate balance Washington is trying to strike between limiting Iranian influence and allowing Iraqi leaders to determine their own path to defeating the Islamic State.
U.S. officials have said Iraq did not ask the U.S. to provide air support for the Tikrit offensive, even though the U.S.-led military coalition has been conducting airstrikes in much of Iraq since August and has deployed hundreds of U.S. soldiers to try to regenerate an Iraqi army that collapsed last June.
Dempsey said Iran and its proxies have been operating inside Iraq since 2004, but the Tikrit campaign signals a new level of involvement.
"This is the most overt conduct of Iranian support, in the form of artillery and other things," Dempsey said in response to questions from members of the Senate Armed Services Committee. "Frankly, it will only be a problem if it results in sectarianism."
He said that about two-thirds of the force seeking to retake Tikrit is comprised of Iranian-based Shiite militia fighters. Iraqi government troops make up the other third. Tikrit, the hometown of former Iraqi President Saddam Hussein, is a predominantly Sunni city.
"If they perform in a credible way" and rid Tikrit of Islamic State control, "then it will, in the main, have been a positive thing in terms of the counter-ISIL campaign," Dempsey said.
Earlier on Tuesday, the U.S. general overseeing the military coalition fighting in Iraq told a House panel that the campaign has killed more than 8,500 Islamic State fighters since its bombing campaign began in August. Army Gen. Lloyd Austin, the commander of U.S. Central Command, said the Islamic State, which has controlled key parts of northern and western Iraq since last summer, is no longer capable of seizing and holding new territory.
Austin said that in addition to killing at least 8,500 Islamic State fighters, the U.S.-led bombing has destroyed "hundreds" of the group's vehicles, tanks and heavy weapons. The bombing also has degraded the group's ability to generate revenue by striking oil refineries and crude oil collection sites, particularly in neighboring Syria.
"The fact is that he can no longer do what he did at the outset, which is to seize and to hold new territory," Austin said.
Austin made the remarks in his prepared statement at a hearing on President Barack Obama's request for new legal authority to execute the military campaign against the Islamic State. Austin is a former commander of U.S. forces in Iraq.
The general was speaking amid new uncertainty about the direction of the battle against the Islamic State as Iraqi forces, including Iranian-supported Shiite militias, opened a counteroffensive against the Islamic State in the city of Tikrit.
Asked about Iran's military participation in the battle for Tikrit, which began on Monday, Austin did not describe the nature or extent of Iranian involvement but stated flatly, "There is no cooperation between U.S. and Iranian forces."
The general said U.S. intelligence sources allowed him to foresee Iran's involvement in the Tikrit fight.
"The activity in Tikrit was no surprise," Austin said. "I saw this coming many days leading up to this. It's a logical progression of what they have been doing in the east of the country, but we don't coordinate with them," he added, referring to the Iranians.