Why are European nations concerned about their security in relation to the Russia-Ukraine conflict?

European nations are justifiably concerned about their security as Russia now poses a real threat of potential attack. They understand that if Russia succeeds in Ukraine through concessions or Western withdrawal, it would embolden Putin to pursue further territorial ambitions. Dr. Malcolm Davis explains that a U.S. withdrawal from NATO would achieve one of Putin's major goals and incentivize Russian aggression. If Ukraine falls and NATO is weakened, Russia would likely move against NATO members within the next year or two, directly threatening European security. The current situation represents a critical inflection point for continental stability.