Amid US-Iran tensions and calls by Iraqi parliamentarians for US troops to leave Iraq, the situation on US bases around the country is tense. There is uncertainty about what comes next, after five years in which US forces had been deployed to Iraq to help, train, equip and advise Iraqi forces during the war on ISIS. A leaked letter on January 6 led to controversy, as it appeared US forces might be suddenly leaving.The mysterious letter was drafted to Staff Lieutenant General Abdul Amir of the Iraqi ground forces, who is also deputy chief of staff for operations and a key leader in Joint Operations Command, Baghdad. The US said it would be “repositioning forces over the coming days and weeks.” The letter said there would be a lot of movement using CH-47 Chinook, UH-60 Black Hawk and AH-64 Apache helicopters. Forces would be moving at night “to help alleviate any perception that we may be bringing more Coalition forces.” It was to be signed by Brig.-Gen. William Seely, a US Marine and head of the US military’s task force in Iraq.There were quick questions about the letter’s authenticity. When it did turn out to be real, there were questions about a translated version of it being circulated and why it wasn’t signed. It appeared later to have been leaked by an Iraqi official and that it was not in its final form. But that leads to questions about why the Iraqis had seen it.It turned out that the letter lacked the clarity that underpins what the US will do next in Iraq. US Secretary of Defense Mark Esper said that there had been no decision to leave Iraq. Lara Seligman at Foreign Policy tweeted that US Chairman of the Joint Chiefs had said the letter was released by mistake. It came after a phone call between him and head of CENTCOM General Kenneth McKenzie.The letter controversy exposed what appeared to be lack of coordination in the chain of command, stretching from Baghdad to the White House. But that only underscores the general lack of certainty about how the US will stay in Iraq if it is asked to leave, and where the 5,000 US personnel might go if they do “reposition.” The US wants to make sure there are sufficient forces to confront any threats, even if they do leave some key bases. There are many considerations. For instance there are other Coalition personnel involved in Iraq.On January 5, the US-led Coalition noted that although it was committed to fighting ISIS, the rocket attacks on US bases over the last months and the recent tensions after the US killed Iranian General Qasem Soleimani meant they had to change posture. “As a result we are not fully committed to protecting the Iraqi bases that host Coalition troops. This has limited our capacity to conduct training with partners and to support their operations against ISIS and we have therefore paused these activities.”With operations paused, the US must review the bases where its forces are located and where they might move or consolidate. That includes Camp Taji and Ayn al-Arab, key bases the US has used. There are also forces at Balad Air Base and apparently at Qayarrah or Q-West. There were forces at K-1 near Kirkuk, because those were the forces affected by the December 27 rocket attack that led to this crisis. There are also US forces in Security Force Assistance Brigades with the Peshmerga and with Iraqi divisions in Nineveh near Mosul.One issue facing the US in Iraq is that in December 2018, US President Donald Trump announced the US would leave Syria and move forces to Iraq. At the time he said that Iraq could be used to “watch Iran.” Iraqi politicians condemned his comments, but he reiterated them in January 2019. Now after the strike on Soleimani and the killing of Kataib Hezbollah leader Abu Mahdi al-Muhandis on January 3, it isn’t clear how much longer US forces will remain in some bases in Iraq. Could they go to Syria, the country that the US said it wanted to withdraw from? Could the US simply withdraw from both countries? That seems unlikely in the near-term. A more reasonable scenario is that the US repositions some forces to northern Iraq’s Kurdistan region, to Kuwait, as well as a handful to Syria.The US was already in the process of handing over more areas on Iraqi bases to the Iraqis since the end of the war on ISIS. The idea was that Iraqis would be doing more of the training and operations that the US was once involved in. Iraq was supposed to be conducting its own drone surveillance and strikes on ISIS locations. Over the last year, Iraq has done that as part of its “Will of Victory” operations, now in their eighth phase. This means the US was ready to reposition some forces anyway. But the letter indicates that movement at night, and a quiet withdrawal from some areas may not go as thought.The US has to remain vigilant as pro-Iranian groups, such as Asa’ib Ahl al-Haq, Kataib Hezbollah and others may want to try to strike at the US based on orders from Tehran and the vows they have made for revenge. Those groups have to wonder if more US airstrikes on them could be possible if they make threatening moves. Many of these Iraqi-based Shi’ite militias are not labeled terrorists by the US or can be considered terrorist groups due to their links to Iran’s IRGC. That gives the US a kind of open season on striking them, if Washington desires to do so.