For decades, Poland has depended on the US for its defense. But with Donald Trump signaling a possible pullback of American forces from Europe, alarm is growing in Warsaw and across NATO’s eastern flank.

Poland is building up its own military power, deepening ties with Nordic and Baltic partners, and thinking harder about how it can deter Russia on its own terms, including increasingly the question of nuclear deterrence. At the same time, Poland is lobbying hard for a permanent US military base, as it seeks to make the ongoing US review of force posture in Europe work in its favor.