An American army general directly threatened Russia with war.
https://www.youtube.com/watch?v=-wCwJ8pfXXo
Russians are taking the threat seriously and are currently performing extensive civil defense drills for 40 million people, who are test-driving the nuclear shelters and hazmat suits.
Prior to that, Americans stopped the bilateral talks with the Russians over Syria and are now contemplating a military solution to overthrow Syrian legitimate government which they don’t like because they prefer the jihadists, according to a recent leak.
The Russians responded to this “leak” by stating that Syrian army is under their defensive umbrella and any attacking aircraft will be promptly taken down without much investigation where it came from. They also mentioned that “stealth” is bullshit and that their radars see American “invisible planes” just fine.
https://www.rt.com/news/361800-russia-syria-usa-aistrikes/
Essentially, Syria is now a no-fly zone for America and their slave-countries. Technically, they can fly, but they cannot perform combat actions. OK, technically they can perform combat actions too, once.
America can now back down and try to achieve their goals in some way that is less hazardous. But that’s not the America we all know. More likely, they will try to immediately push against the imposed boundaries.
But let’s put it this way. Russia is not really bathing in money. Nuclear shelters for 40M people cost serious money. Massive drills that encompass such a huge portion of the populations are also expensive. This means they are perceiving a serious and direct danger of an all-out nuclear war. And I don’t mean all-out for Harambe.