The Pentagon issued a statement on Wednesday expressing concern about a new Turkish military buildup along the border of northeast Syria, warning Turkey against carrying out military retaliation over new US sanctions.
The Pentagon statement warned they would consider any “unilateral actions into northeastern Syria,” particularly targeting US personnel present in the area, would be “unacceptable” for the US.
Northeastern Syria is controlled more or less entirely by Syrian Kurdish forces, with US troops in the country backing them. Turkey has long wanted to invade this territory to chase out the Kurds, and has expressed willingness to confront the US in doing so, if necessary.
Turkey clearly has long prefer not to fight the US, hence their oft-threatened invasion hasn’t happened. The mounting tensions with the sanctions, however, may be convincing Turkey to be more aggressive.
Turkey’s government probably will want to assert itself again in the region, and that might involve a move against the Kurds, or kicking the US out of a base in Turkey. Its highly unlikely they’d attack the US directly, but the Pentagon apparently thinks its possible enough.