Even as President Donald Trump declared mission achieved and said he will pull U.S. troops out of Syria, American forces moved this week into Manbij, one of the most contested Arab cities in eastern Syria, setting up night patrols, and establishment of a visible presence.

Back in 2016, U.S. bombing enabled a Kurdish-led militia to capture Manbij from the so-called Islamic State, but Turkey has defined its sights on taking over the city, as has the Assad regime. And now with Trump's announcement, which undercut previous U.S. government plans to stabilize the northeast Syrian region following a devastate U.S.-backed military attack on Raqqa, Manbij appears to be up for grabs.

Turkish President Recep Tayyip Erdogan Wednesday renewed his demand that the Kurdish forces–which are closely linked to the Kurdistan Workers Party at war with Turkey for over three decades–get out of Manbij.

Turkey” will not stop until all regions” under control of the Syrian branch of the PKK, principally Manbij, “are secured,” he said following summit talks with Russian President President Vladimir Putin and his Iranian counterpart, Hassan Rouhani.

The U.S. and Turkey held high level talks Friday–including a Trump-Erdogan telephone call–about the issues now dividing the two NATO allies, including the future of Manbij. The prospect of a shift in overall control without doubt rattled the Kurdish forces on the ground.

Turkish state media and Syrian opposition media reported 300 U.S. troops arrived in the city on Monday in several escorts. They said U.S. forces-out, which had previously been stationed outside the town and built only occasional forays into the center , now are doing regular patrols, particularly at night, and may have set up an office in the city for the first time.

The Pentagon would not confirm the numbers but did not dispute reports of troop motions. It connoted the decision was taken locally.” Commanders are delegated the authority and the responsibility to position the number of people and resources needed to accomplish the mission and to protect themselves ,” said Eric Pahon, a Pentagon spokesman.” Occasional modifications to force size would therefore be normal .”

U.S. officials said the details of the redeployment are classified, but the aim is clear: to reassure the Kurdish People's Protection Forces, who lead the Syrian Democratic Forces in control of Manbij, that they are protected and secure.

In eastern Syria, the Kurdish force, known by the initials YPG, has all but abandoned frontline ground operations against ISIS in order to join Kurdish brethren under attack by Turkish and Syrian rebel forces in Afrin , northern Syria. Afrin fell in mid-March, and with Turkish backing, Syrian rebels are now trying to oust Kurdish forces from other areas.

Turkey's state news agency Anadolu reported Tuesday that the U.S. is planning to build two basis close to Manbij and said that construction materials and heavy equipment had been transported to a village north of Manbij. Construction of the two basis would put U.S. forces in the immediate vicinity of the Turkish-controlled zone in northern Syria, which Turkey captured with the aid of Syrian rebels in March of 2017, Anadolu said. U.S. officials would not confirm this.

In the midst of this tense situation, with Turkey and Syrian rebels fighting the same Kurdish force that the U.S. was relying on to fight ISIS, Trump's decision, which he reportedly communicated to his top security consultants Tuesday, hurls almost everything in eastern Syria into disarray and disarray.

It's not just that the relatively small U.S. presence in Syria- an estimated 2,000 U.S. troops and about 200 civilian personnel- are a key factor in stabilizing the region and prevent further strife as hundreds of thousands of displaced seek a route to get back to their homes. The big question is how to avoid an enormous strategic setback, for other players are only too eager to fill the vacuum the U.S. withdrawal would create.

Trump's decision, if he follows through on it, raises three three separate questions:

One is how to continue the battle against ISIS, which recently grabbed new territory in eastern Syria, capitalizing on the disarray in the ground forces that oppose it.

A second issue is how to prevent the Assad regime, aided by its Iranian ally, from moving into the region the U.S. helped clear with the aid of its Kurdish ground force ally.

The third issue is whether to allow Turkey to fill the vacuum, especially in Manbij, in light of severe strains in the U.S. Turkish relationship.

Strains in U.S.-Turkish relations arise during the Obama administration when the two NATO friends failed to agree a common strategy on Syria. The U.S. refused to provide a military guarantee for Turkey's proposal to establish a safe zone inside Syria, which might have stopped the outpouring of refugees. In the event, Turkey wound up hosting at last three of the five million who fled Syria.

When Islamic extremists started taking over towns and regions in Syria without any resistance by the Assad regime, the U.S. repudiated Turkey's contention that Assad was to blame and declared it would mount operations merely against ISIS, dismissing the Syria government.

Making matters worse for Turkey, the U.S. decided to ally with the PKK's Syrian affiliate, the YPG, as the ground force-out to fight ISIS. With the U.S. air supporting, the YPG deposed ISIS from township after township but went on to expel the Arab population as well, forcing tens of thousands more to flee to Turkey. In the operation to clear ISIS from Raqqa, the self-declared capital of the Caliphate, the U.S ., over the vehement objections of Turkey, provided more advanced weapons to the Kurds.

Erdogan's increasingly autocratic regime has added to the tensions. Turkish authorities plan to try the Rev. Andrew Brunson, an evangelical American cleric long based in Izmir, and also arrested two U.S. U.S. Embassy employees. All are alleged to have had a relationship to a U.S.-based Muslim cleric Fethullah Gulen, who Erdogan alleges organized a failed coup in July 2016. Erdogan has demanded the United State extradite Gulen, but U.S. officials say Turkey has failed to provide sufficient evidence that he is responsible for the coup attempt.

Turkey's media, dominated by pro-government outlets, have moved from criticism of U.S. foreign policy to contempt. The Daily Sabah, which is practically an official organ, summed up the mood after Trump's declaration of intent to pull out of Syria.” Trump's strategy: Turning tail and leaving others to clean up Obama's Syria mess ,” read the headline it devoted an unsigned editorial Friday.

” It is no secret that the United Country has a long history of catastrophic military interventions ,” said here Daily Sabah.” Washington likes to follow a three-step plan when it comes to overseas campaigns. Deploy troops, proclaim victory, then get the hell out. This time-tested approach is guaranteed to leave behind a total mess, which tends to turn conflict zones into breeding ground for terrorist groups .”

But however distasteful the prospect of turning over the region to Turkey might be, the alternative is potentially more more harmful to American interests. The Assad regime, which is eager to restore its sovereignty in Manbij, has few loyal troops and must rely on Hezbollah, the Lebanese militia on the U.S. terrorism listing, and other militias under the command of the Iranian Revolutionary Guard Corps, the IRGC. In Manbij, a largely Sunni town, the arrival of those Shiite militias would be a worse nightmare than the arrival of ISIS in January 2014.

For Iran, the departure of U.S. forces-out from Syria is being heralded as a victory for the” Axis of Resistance ,” the blended anti-western forces of Iran, Syria and Hezbollah. Tasnim, a news outlet affiliated with the IRGC, illustrated a U.S. withdrawal as an Iranian victory.” If American forces pull out of Syria as Donald Trump has promised, this will be considered Washington's acknowledgement of its defeat and a great victory by the axis of resistance in this country ,” analyst Hassan Hanizadeh told the agency, as quoted by the Middle East Institute, a Washington think tank.” America's exit from Syria will lead to a gradual isolation of Saudi Arabia, France and England in the region .”

The IRGC has stated its territory intent in Syria- to acquire a land corridor a procure road to resupply Hezbollah in its continuing showdown with Israel. The Trump administration has declared its intention to prevent Iran from having free access to any such corridor.

Ironically, the battle against ISIS may be the lesser fret for Washington, for there are signs Washington will ask Baghdad to send troops into Syria to fight the revolutionary Islamist group. Iraqi Prime Minister Haider al Abadi said Sunday he'd created the possibility of cross-border operations with Iraqi commandants one day earlier and it is possible that Iraq will send forces into eastern Syria.

U.S. officials say there is a legal justification for a cross-border intervention because ISIS had attacked Iraq from Syria. The big question is whether it's a good idea.

As one of those officials asked,” Do we really want to support another country invading Syria ?”

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