At the eastern edge of the European Union, Poland has begun reinforcing its border crossings with Ukraine — a quiet but consequential act that speaks to how profoundly the security calculus of an entire continent has shifted. What was once a corridor of commerce and human connection is now also a strategic threshold, demanding vigilance in an era of deepening regional instability. Poland's decision reflects not merely a national concern, but a collective European reckoning with the long shadow cast by ongoing conflict to the east.