If Nato joins the conflict, they will very quickly get aquatinted with Kinzhal, Tsirkon & Avangard hypersonics (un-interceptable as of now) loaded with conventional warheads (non-nuke) followed by a barrage of their other (of larger variety and longer range than anything western) ballistic stand-off weapons. For now, Russia has the advantage in ballistics and layered air defense (S-300, 400 & 500, Pantsir + electronic warfare systems). They also have an advantage in field artillery (more variety & longer range than anything western). Even the US president had to admit the hypersonic complication.