What we know about the planned Turkish offensive in northeast Syria

In the last 24 hours, the United States announced it would begin withdrawing from positions opposite the Turkish border in northeast Syria, in order to make way for a “long-planned operation” by Ankara to invade the region.
The decision came after a phone conversation between the presidents of Turkey and the United States.
In an official media release by the Office of the Press Secretary, the US side confirmed that its forces would not partake in the Turkish military operation and that they would withdraw from all areas of northern Syria (east of the Euphrates River) where Turkey planned to conduct its incursion.
The scope of the anticipated Turkish offensive is unknown at this time, however, it is generally believed that it will extend at least thirty kilometers into northern Syria from Turkey’s borders between Kobane to Ras al-Ayn.
Although the US statement made vague references to captured ISIS militants becoming Ankara’s responsibility, it failed to mention that the Turkey was launching its operation with the aim of neutralizing Kurdish-led Syrian Democratic Forces (SDF) units immediately south of the country’s borders.
Ankara considers the SDF to be a terrorist organization with links to the PKK (a Kurdish insurgent group based in Turkey with which the country’s military has been at war with for over three decades).
In a flurry of official and semi-official statements, SDF has accused the US of stabbing it in the back, creating a regional catastrophe and ‘not living up to its commitments’ to preserve the so-called ‘security mechanism’ for northern Syria that was originally arranged to prevent the operation which now looms but seems to have failed.
Amid the US withdrawal which has now been confirmed by video evidence and Western mainstream media groups with links to American military sources, reports – still unconfirmed – have since arisen claiming that the Syrian Army is planning to enter Manbij city.
More provable based on media pictures, there are also reports that Russian forces have established a bridge crossing over the Euphrates River in Deir Ezzor province offering a link between Syrian government and SDF lines.
Finally, SDF-linked sources on social media claim that the militia group has begun sending reserve forces from Raqqa and Deir Ezzor provinces in order to bolster the 370 kilometer front-line which represents the Turkish-Syrian border east of the Euphrates.
In the event the Turkish offensive goes ahead, it is highly unlikely that lightly-armed SDF units (no longer backed by US air support) will be able to withstand against the invading force.
The terrain of northeast Syria which is relatively flat only favors an attacking force, rather than a defensive force.
In addition to this, the Turkish-led invasion force is likely to greatly outnumber the SDF along the entire line of contact and will have an overwhelming firepower advantage in the form of mechanized units, artillery and unchallenged air dominance.