NATO has to assure their members that they would stand by them.
Ukraine isnt in NATO officially.
Are you saying NATO wants to give ‘assurance’ to its own members that they’ll provide help if Russia were to enter NATO territory by ‘helping’ a non-NATO country? Don’t you think its a bit ridiculous to give billions of dollars of weapons (thus weakening themselves) to a non-NATO country just to ‘prove’ to its eastern European members that NATO will ‘help’? U.S. already has military bases in Germany, Poland and Baltics, one would think large number of U.S. soldiers just being in Eastern Europe and multiple NATO countries having nuclear weapons would be enough of a deterrence for Russia to not invade.