We have repeatedly emphasized that the Y.P.G. has left Manbij and that our forces pose no threat to Turkey’s national security. We believe that Mr. Erdogan fears not the presence or the absence of any given military force but the peaceful and democratic coexistence of Arabs, Kurds, Christians and others in northeastern Syria.Mr. Erdogan cannot exploit such coexistence. He plans to use the Turkey-backed Islamist opposition in Syria to invade Manbij, just as he used it in the nearby Azaz, Jarabulus and Afrin areas.While Turkey claims to be returning these territories to their “true owners,” Mr. Erdogan is instead dooming Syrians to foreign occupation and militia rule and making the prospect of peace after eight brutal years of war even more elusive.Nowhere is this more evident than in Afrin, where Turkey has been accused of enlisting former members of the Islamic State and militias with ties to Al Qaeda to decimate the peaceful region and its autonomous administration. Turkey’s incursion into Afrin in northern Syria displaced around 300,000 people, and the militias backed by Turkey seized, looted and destroyed property of Kurdish civilians.If the United States allows Turkey to attack Manbij, that will be our fate, too.Unfortunately, it seems that global powers are still willing to play Turkey’s games. Mr. Erdogan’s “road map” for Manbij does not serve and reflect the interests of its people. He also proposes the establishment of a “safe zone” in the wake of an American withdrawal, a plan that Mr. Trump appears to have, in some form, agreed to.We are not opposed to the concept of a safe zone. We believe that it is possible for the United States to withdraw its forces from our region without abandoning our people. However, we will not accept any Turkish incursion into the areas we have liberated, no matter the words used to describe it.Any “safe zone” in northeast Syria must be guaranteed by international forces and not by the Turkish troops and jihadist militias massing at our borders. An international safe zone would ensure that Turkey’s borders are protected, without subjecting the people of northeast Syria to the mercy of Mr. Erdogan’s proxies. It would also facilitate the continuing reconstruction efforts taking place in our region, which are key to peace and stability.