so are the NATO countries for providing weapons, manpower and special forces to Ukraine. The strike on Saki airbase was most likely from long range HIMARS rockets which can spread bomblets over a wide area. Now the chances of escalation to mainland Europe are extremely high and very soon we might see Russia striking couple of airbases in NATO countries in retaliation.
It's apparently SOF or partisans who infiltrated the base and detonated aircraft and ammo.
I don't think it's gonna be serious enough for Russia to attack NATO. I doubt it's enough for the Russians to even declare war on Ukraine.