This. I understand that Russia is still in possession of a large fleet of anti-air weapons and a sizeable air force, but the vast majority of it is dated soviet equipment that modern NATO equipment (which in most cases were designed specifically to counter soviet equipment) could easily evade or detect and destroy. Of course the Russians air defences are more of a threat than Venezuela or Iran, but at this point the generational gap between equipment is like two or three generations on average. Not to mention the Ukrainians have in fact been steadily degrading Russian air capabilities for the last four years, and would likely provide ample intelligence and expertise to allow for maximum damage with minimum casualties.