Hours after images of migrants climbing a border wall in San Diego went viral, the Homeland Security Department deployed razor wire Wednesday to prevent a repeat. The immigrants, who said they were the vanguard of the caravans streaming north through Mexico, ascended the fence Tuesday in a display of defiance. Video and photos showed them cheering and jeering atop the slat-style fence. Although no arrests or confrontations were reported, Homeland Security took immediate steps to try to keep others from climbing by deploying concertina wire, which coils over itself, creating a thorough barrier. “As we have said repeatedly, being a...