“The start of the HMC process reflects the evolving U.S.-Iraq bilateral relationship under the Strategic Framework Agreement, and it underscores our commitment to deepen our security cooperation to advance stability within Iraq and the region.”

The move would constitute a major achievement in relations between the two countries, marked by a years-long effort to battle the IS, considered a common enemy.

The talks, which are known formally as the Higher Military Commission, come just days after Iran-backed forces in Iraq launched a barrage of missiles on a U.S. military installation, which injured at least four service members and one Iraqi.

The defense officials said the formal discussions would have started sooner if the latest chapter in the ongoing war between Israel and Hamas had not occurred.

At least 60 attacks have been launched on U.S. forces in Iraq and more than 90 in Syria. Iran-backed militants blame the United States for the tensions, citing its support of Israel.

There are still roughly 2,500 American troops serving in Iraq and 900 in Syria working to head off a resurgence of the Islamic State.

U.S. officials have not said how soon troops might leave, if they are, indeed, sent out of Iraq.

“We are going to — together with our Iraqi partners — help determine the shape of the future U.S. military presence in Iraq, and at the same time, ensure an Iraqi lead enduring defeat” of the Islamic State, said a senior defense official, speaking on condition of anonymity and quoted from an officials transcript from the Defense Department.

“But beyond that, we won’t speculate,” the official said.

The United States has been working with Iraq for a decade to regain control of territory from the Islamic State, and deployed troops there to train and advise Iraqi security forces to ensure IS doesn’t regain control.

But Iran, Iraq’s powerful neighbor, holds significant sway over the Iraqi government and the Shiite militias that are somewhat under Iraqi government control.