Last month, fighters with the Syrian Democratic Forces (SDF), a 60,000-strong Syrian militia that has been Washington’s primary partner in the U.S.-led campaign against the Islamic State (ISIS), captured the Syrian town of Baghouz, ISIS’ last remaining stronghold. Although ISIS has not been fully eliminated as an organization, Baghouz marked the final territorial defeat of the group, which at its peak in 2014 controlled nearly 40,000 square miles in Iraq and Syria.
Yet the territorial defeat of ISIS is not the end of the U.S. mission in Syria, where today some 2,000 American troops help the SDF administer and control the northeastern third of the country. Although U.S. President Donald Trump announced in December 2018 that he would be withdrawing all American forces from Syria, he has since partially reversed course—in March, Trump affirmed that he is “100%” in favor of leaving a residual presence of 400 U.S. troops in Syria.
The question now is how Washington can use this residual presence to secure its long-term interests in the country: countering Iranian influence, preventing a return of ISIS, isolating the regime of Syrian President Bashar al-Assad, and protecting the people of northeastern Syria from further slaughter. Achieving these goals will require the United States to use its troop presence to prevent the Syrian regime from attempting to retake the country’s northeast with Iranian and Russian assistance. At the same time, the United States must reshape the SDF into a force capable of providing long-term stability on the ground.
A major obstacle to the integrity of northeastern Syria, however, is Turkey. Ankara perceives a serious threat from the People’s Protection Units (YPG), the Syrian-Kurdish militia that dominates the SDF. The YPG is the Syrian wing of the Kurdistan Workers’ Party (PKK), a designated terror group that has been waging an insurgency against Turkey for more than 30 years. Ankara seeks to create a “safe zone” stretching some 20 miles deep into SDF-held northeastern Syria, from which it would expel the YPG.
Source : https://www.foreignaffairs.com/articles/turkey/2019-04-09/saving-northeastern-syria?fbclid=IwAR1r5tr4zcmEVcowQe_3sH3KZeW_JLt5uFEEXCeWdoYBt_bT73CVg9-Bfnk