Of course but they can get all the countries that are not part of NATO, wait a few years and then come back with full strength, new ressources, new alliances and then we can ask ourselfs if there was not a place in time we could have prevented this…
The theory of sound, but most countries look towards their own self-interest first (unfortunately), so it may be harder to get all the countries together than you state.
Still it’s something we should try, it’s better to unite around peace and stability beforehand, than after a war.