The US withdrawal of its troops from eastern Syria is an unprecedented move, coming after six months in which Washington had laid the groundwork for a longer-term commitment. US Chairman of the Joint Chiefs of Staff Joseph Dunford recently said that the US had completed training only 20% of the 30,000 local stabilization forces. In addition, the White House, National Security officials, the State Department and the Pentagon have previously suggested that the US would remain in Syria until Iranian-commanded forces leave. This was a developing policy, and the US was committing more diplomatic staff to Syria, including appointing James Jeffrey as an envoy.The US-led coalition has also been carrying out a large number of air strikes in recent weeks. Between December 9 and 15 the coalition carried out 208 strikes. And ISIS isn’t beaten. Estimates say there are thousands of fighters, some of them the most dangerous and hard-core foreign fighters. The Syrian Observatory for Human Rights said that ISIS has executed hundreds of prisoners recently. Beyond that, there are hundreds of ISIS detainees held by the Syrian Democratic Forces, the main US partner on the ground, which has been fighting ISIS.The US decision now throws into question everything that has been done in the past four years.In August 2014, ISIS attacked Sinjar in northern Iraq, and this propelled Syria to first come to serious attention by the US. The Kurdish People’s Protection Units (YPG), a lightly armed group, helped save tens of thousands of Yazidis from Sinjar in northern Iraq, opening a corridor for them to flee to Syria. The Obama administration ordered air strikes and humanitarian air drops to help the besieged Yazidi minority. ISIS systematically murdered thousands of Yazidis and enslaved 5,000 women in atrocities that shocked the world. This galvanized up to 79 countries to support the coalition.The US began to seriously help the YPG in 2015 and eventually encouraged it to form the SDF, an umbrella group of fighters who liberated one town after another in eastern Syria. ISIS, which seemed invincible in 2014, was pushed back, and the SDF crossed the Euphrates River to liberate Manbij in 2016. Scenes of women removing the black chadors that ISIS forced them to wear, and the sight of people smoking and singing, became normal. Women fighters who joined the YPG told stories of fighting ISIS. Hundreds of foreign volunteers, some from the US and UK, went to join the YPG, as international volunteers had done in Spain against fascism. In 2017 came the liberation of Raqqa, the capital of the “caliphate.” This cemented a unique and momentous partnership for the US.But it was a partnership with problems. Turkey viewed the YPG as the Syrian version of the Kurdistan Workers Party (PKK) and therefore saw its fighters as terrorists. The US initially told Turkey that its relationship with the YPG was temporary and tactical – to fight ISIS. But by 2017, with the SDF and US fighting side by side, it was clear this was longer term. Turkey decided to move into parts of northern Syria to prevent the Kurdish groups from expanding, and in January 2018 Turkey also invaded Afrin, a Kurdish area held by the YPG. This was designed to send a message to the US that its allies could be defeated and Turkey would not allow further expansion.Turkey had reasons to be suspicious. In 2015, a PKK ceasefire in Turkey had fallen apart, and Turkey fought battles in eastern Turkey. It also launched air strikes and incursions into northern Iraq. Turkey grew concerned about other Kurdish aspirations, opposing the Kurdistan independence referendum in northern Iraq.Turkey has grown closer to Russia and Iran over the last several years. It began to work with Russia and Iran to discuss the future of Syria, sidelining the US. Turkey also increasingly threatened an operation into Manbij and northern Syria.The US agreed to joint patrols with Turkey over the summer, but this didn’t placate Ankara. Instead, Ankara decided to buy the S-400 air-defense system from Russia, even as it was interested in buying the F-35 jet fighter and Patriot missiles from the US. This was unprecedented for a NATO ally. But Turkey has found that it shares concerns with Iran and Russia, and that it is comfortable working with them.MEANWHILE, THE Trump administration is isolated. While Turkey and Qatar have become close allies, the US was embarrassed by its ally Saudi Arabia, after the Jamal Khashoggi murder in October. Saudi Arabia was supposed to provide hundreds of millions for stabilization funding for eastern Syria. Only $100 million was sent in October. The Trump administration wanted Arab allies to pay for eastern Syria, but that hasn’t happened yet.In addition, the State Department and Defense Department don’t agree on what to do about eastern Syria. The State Department wants to work with Turkey. Other administration professionals view the Turkey relationship as key, and have wanted to support the Syrian opposition groups that oppose Bashar Assad, after Trump decided to walk away from them earlier this year. The Pentagon wants to defeat ISIS, but it also wants stabilization. Some in the Trump administration, such as Secretary of State Mike Pompeo and National Security Adviser John Bolton, saw eastern Syria as an important piece of Syrian real estate, to be used to barter with Iran. The Middle East could be leveraged to get Iran out of Syria. Israel also thought this was a good idea, since it also does not want Iran in Syria. James Jeffrey, the Syrian envoy for Trump, visited Israel in September to discuss this. Bolton also noted, while in Jerusalem, that Iran was a threat in Syria.Now Trump wants to leave Syria. He wanted to do so before, but was convinced to stay. The problem is that this will now weaken the US’s hand against Iran and will throw eastern Syria into chaos.Turkey will launch an operation if the US leaves, and the Kurdish fighters who helped defeat ISIS will likely have to fight a new war and perhaps sign a deal with Damascus. This will involve Iran and the Syrian regime entering eastern Syria. A new conflict could result. An ISIS resurgence, already happening in Iraq, could begin again. Iraqi militias already serve in Syria, and so Iraq may be drawn into border areas. Russia will help broker a deal, as it has before with Turkey over Idlib, making Russia the senior broker of the future of Syria.US lip service about the Geneva process and UN resolutions on Syria will be scuttled, as US allies and adversaries see the US isn’t serious. A US withdrawal without receiving anything in return or even fully defeating ISIS could jeopardize US policy in the region and permanently weaken the US hand against Iran.For Israel, it is also a potential threat, as Iran’s “corridor to the sea” that runs through Syria will expand. Iranian influence will grow. If the US officials have put this up to test reactions, it will weaken faith in the US.In addition, US Kurdish allies in the Kurdistan Regional Government have already expressed concern. Masoud Barzani, the former KRG president, spoke with US Special Presidential Envoy Brett McGurk this week about eastern Syria. Now the Kurdish region may also be destabilized.