What are European leaders concerned about regarding a potential Trump-Putin deal?

European leaders are deeply concerned that Trump might rush into a deal with Putin that disregards European security interests while effectively rewarding Russia's aggression. After hastily gathering in Paris to address this radical American pivot, their primary fear centers on how such a hasty agreement could potentially embolden future Russian threats against neighboring states. The urgency of these concerns prompted European leaders to convene quickly, recognizing that any deal made without considering European perspectives could undermine regional security architecture and validate Russia's aggressive actions in Ukraine and beyond.