Hundreds of Central American migrants staged a boisterous demonstration on the US Mexico border Thursday, screaming for President Donald Trump to let them in as US soldiers and riot police put on a menacing show of force…

Vehicle and pedestrian traffic at the busy San Ysidro crossing came to a halt for 40 minutes as dozens of US police wearing helmets and holding rifles formed a line facing the Mexican side of the frontier. Separately, riot police rehearsed deployment movements. US Customs and Border Protection called all of this a “large-scale readiness exercise.”

American soldiers in khaki-colored uniforms set off rockets that exploded with a pungent-smelling white smoke. Helicopters hovered overhead.