Poland is ramping up military spending and border defenses, fearing that it could be one of Russia’s next targets after Ukraine. For decades, Poland has relied on US support for its defense. But now Donald Trump is planning to pull US troops out of Europe, causing alarm for Poland and the other countries closest to Russia on NATO’s eastern flank. Poland is doing everything it can to keep the United States, its strongest ally, on its side. But it is also building up its own military muscle. Poland has recently purchased M1A2Abrams tanks, AH-64 Apache helicopters and F-35 Lighting II fighter jets from the United States. And Poland is building partnerships closer to home, for example with the Nordic and Baltic states — and even considering how it could work with other countries to benefit from their nuclear weapons. Poland’s history explains why it is so afraid of outside threats. During World War II, it was divided by Nazi Germany and the Soviet Union. Now it is determined to keep Russia out and cope with Vladimir Putin’s nuclear saber-rattling.