It's a complicated question. Sending even a few anti-air SAMS and anti-armored vehicle weapons would make matters almost impossible in Ukraine for Putin's take-over quest. It would take little and little cost to turn that conflict into an unending quagmire and Russians would tire of it fairly quickly.
What makes it complicated is Russia could then do the same against US in the ME.
We have the ability to virtually neutralize heavy vehicles and air power being used by Russia in Ukraine, but Russia could cause us a lot of problems in the ME in the same way in response.
Generally, the major powers have an unspoken deal that they won't release, sell or allow to be sold 1.) effective anti aircraft missiles and 2.) weaponry that can take out armored vehicles. That allows the major powers to remain major powers. The major powers draw a line on how they prick with each other for mutual interests.