More specifically, after Russia pulled out of Northern Syria after defending it from ISIS for the last several years (along with the Kurdish militias), the US rolled right in (the US and Kurds are tight; have been for decades) and claimed credit for the whole thing.
So now, the US says they’ll be supporting the Kurds in Northern Syria, which has to piss off the Turks and Iraqis in a major way, since everyone knows the Kurds end game is to establish an independent Kurdistan out of pieces of the three countries.
TIllerson said straight up that the goal was to prevent Assad from re-establishing control over that part of his own country, which incidentally is one of the areas where Assad’s support is strongest.
Sound like this will end well? The US is now officially in the category of “invader” in Syria.