Driving back to his village near the Ukrainian border last Thursday, the mayor had to stop to let a train pass, and assumed he wouldn¡¯t have to wait long. But the flatbed wagons, stacked high with military equipment, just kept coming. He waited for nearly half an hour.

¡°It was a very long train, much longer than usual,¡± recalled Mikolas Csoma, the mayor of Dobra, a previously sleepy village in eastern Slovakia that, over the past month, has become a key artery funneling weapons and ammunition into Ukraine by rail from the West.

The train that delayed Csoma¡¯s drive home was not only unusually long but also signaled a singular escalation in Western efforts to help Ukraine defend itself. It carried an air defense system made up of 48 surface-to-air missiles, four launchers and radars to guide the rockets to their targets, which in Ukraine means Russian warplanes and missiles.