NATO soldiers ARE fighting. The UK has said this outright and others allude to it. The US admits to having CIA and other US "advisors" on the ground. The US has admitted to providing intelligence information, targeting, logistics support, etc. Poland is providing repair and logistics support in and outside of Ukraine.

How many NATO troops are unofficially fighting we may never know.

NATO is providing lots of old and only some new weapons to Ukraine. Part of the issue of old vs. new is that providing a Patriot missile system or a new battle tank to someone who isn't trained on it and for an army where the system/weapon is not integrated doesn't help in the short run.

This isn't a movie where Ukie-Joe hops in the new tank and starts blasting the evil Russkies. It takes months to train a tank crew. It took Ukraine 3 years to train up on the new drone system they were using at the beginning of the war.

If NATO marched in it would more than likely lead to WWIII, and quite likely the end of the world.

Right now BRICS, particularly China and India, who respresent about 1/3 of the worlds population, are remaining neutral militarily but supporting Russia economically because 1) they are making a shitton of money doing it; and 2) they know (China has said this semi-officially) that if the US is successful in crushing Russia they will come for them next.

So if NATO were to march in, BRICS countries would be pushed VERY hard to make a choice. I'd say the odds are about 80% that at least China would start supplying Russia with arms, and if it looked bad for Russia, they would either send troops or most likely they would invade Taiwan to force NATO to split their attention.

Ergo: WWIII, and with 3 or 4 (including the top 2) nuclear powers in open war, the chance for nuclear war and the end of humanity climbs to well over 75%.

Which is why this proxy war over Ukraine is fucking insanity.