The Turkish army is reportedly mobilizing on the Syrian border as of Thursday, January 18, in preparation for military action to clear United States-backed Kurdish militia forces from Afrin district (northwest Syria) and the city of Manbij. This development is in response to reports of US plans to assist in the formation of a reinforced "border security force" - which would include Kurdish troops regarded by Turkey as terrorist elements - that would operate along the Turkish border. Turkish tanks have been observed building up along the border with Afrin, and on Thursday, Turkish officials were dispatched to Moscow to discuss coordination for military operations in the area; Russia has effective control over the Afrin region's airspace, and Turkish airstrikes would require Russian assent. Meanwhile, also on Thursday, Syria warned that its air defense would shoot down any Turkish jets carrying out attacks in Syrian territory, although it is unclear if Syrian forces have the capability to follow through on the threat if forced to do so. It is currently unclear when the threatened Turkish offensive could begin, but observers have warned that such a move could have significant humanitarian consequences.
On Saturday, January 13, news broke that the US has plans to build a new "border security force" composed of about 30,000 personnel, including members of the Kurdish People's Protection Units (YPG) and other allied forces, as part of its ongoing fight against Islamic State (IS). Turkey immediately condemned the announcement, with Ankara stating that such a move would be tantamount to building a "terror army" that would threaten Turkey's domestic security, and demanding that the US withdraw its support of Kurdish forces in the region. The US, for its part, has stated that its intentions have been misstated and that it is not creating a border security force, but is lending support to ensure that "local elements" are capable of providing security to liberated areas inside Syria (including preventing any resurgence of IS).
Turkey and the US, both NATO members, have historically been allied in the ongoing complex Syrian civil war. However, the US's close ties with the YPG, which has become a key ally to the US in the fight against IS in the region, has caused tensions between Ankara and Washington to spike. Turkey views the YPG as an extension of the Kurdistan Worker's Party (PKK), which has been at the forefront of a Kurdish insurgency in Turkey since 1984, and Ankara views the presence of Kurdish troops so near the Turkish-Syrian border as a direct threat.
Individuals in Turkey are advised to monitor developments to the situation, adhere to all advice issued by their home governments, and avoid travel to within 10 km (6 mi) of the Syrian border due to the high risk of terrorism and other violence.