NATO didn't start the war. Putin ordered Russian armies to cross the international frontier on the evening of February 23.
So you can't identify any NATO armies on Ukranian or Russian soil.
You can't point to an actual Ukranian application to join NATO.
You can't even point to a NATO invitation to Ukraine to join NATO.
You are reduced to using the George Dumbya Bush excuse that there possibly might be a threat to Russia at some indeterminate point somewhere in the future, and you are going to invoke preemptive war for a hypothetical threat in the future