The head of the US military's Task Force Iraq, Brigadier General William Seely, sent a letter to the head of Iraq's joint operations command, a copy of which was seen by several news agencies.
It came in reaction to a United States precision drone strike on Baghdad that killed Iranian general Qassem Soleimani and top Iraqi commander Abu Mahdi al-Muhandis, among others.
The letter appeared to have been sent by Brig Gen William H Seely, head of the United States military's task force in Iraq, to Abdul Amir, the deputy director of Combined Joint Operations.
The US military has said it will withdraw from Iraq and would begin repositioning its forces over the coming days and weeks, less than 24 hours after the Iraqi parliament demanded their expulsion.
The letter's authenticity was confirmed by multiple reports and was reportedly delivered to Iraqi officials, but USA officials later pushed back on the media's characterization of the letter as signaling a "withdrawal". It was not immediately clear if all roughly 5,000 USA troops would leave Iraq.
But there's been no decision made to leave Iraq.
A US military official in Baghdad told NPR the operation involves what he described as a "limited repositioning of troops mostly from the Baghdad area to places that are likely to be safer". This increased traffic will include CH-47, UP-I-60, and AH-64 security escort helicopters. "But the American people should know we'll make the right decision".
"That letter is a draft, it was a mistake, it was unsigned, it should not have been released", said Milley, adding the letter was, "poorly worded, implies withdrawal, that is not what's happening". It said helicopters would be travelling in and around the Green Zone as part of the preparations.
On Monday afternoon, social media and journalists starting spreading a letter purporting to announce a US withdrawal from Iraq.
The Iraqi resolution specifically calls for ending an agreement in which Washington sent troops to Iraq more than four years ago to help in the fight against the Islamic State group. However, this would seem to contradict the last sentence, which talks about "your sovereign decision to order our departure".
We will continue to update this story as new information becomes available.