NATO did not put boots on the ground. They discussed it a lot and armed Kosovans but did not move into the ground. This Wash Post article is titled " Kosovo Land Threat May Have Won War " for a reason
https://www.washingtonpost.com/wp-srv/national/daily/sept99/...
NATO, er USA, has a lot of options to inflict pain and lots of it. A few Tomahwaks can cripple the best factory, power supply etc (they can link it to aiding the military so no war crime). They can escalate until the other side surrenders
> KFOR entered Kosovo on 11 June 1999 two days after the adoption of UN Security Council Resolution 1244. At the time, Kosovo was facing a grave humanitarian crisis, with military forces from Yugoslavia in action against the Kosovo Liberation Army (KLA) in daily engagements.
Note that daily engagements were ongoing at this point.
NATO, er USA, has a lot of options to inflict pain and lots of it. A few Tomahwaks can cripple the best factory, power supply etc (they can link it to aiding the military so no war crime). They can escalate until the other side surrenders