The CIA will now pull out their ‘we really didn’t want to do this, but now we have to’ plan.
Expect major events, specifically aircraft. And soon.
No planes from the US ... no way to defeat the S400 system = downed US plane. Any major event will involve Turkey ... Turkey imagining that they can drive the Russians out ... prediction if that comes to pass: Turkey on its own; no NATO; and Turkish incursion is over in 15 minutes with major Turkish losses (essentially Army, AF and Navy eliminated); Turkey no longer able to stop the Peshmerga. This last is why I do not think Erdogan would be so foolish, but its the vainglorious Islamic pride so one can’t say for certain.