After Nice, feds say nothing left to chance at conventions

U.S. Secret Service officials say security planning for the Republican and Democratic national conventions took into account large-scale terrorism threats like the vehicle attack that occurred in France.

In Philadelphia, site of the Democratic National Convention, the Secret Service’s top agent said Friday “there is nothing we leave to chance.”

Agents will sweep permitted vehicles for explosives and turn away general traffic in security zones set up around the convention sites.

Philadelphia police will use rolling street closures and uniformed officers to protect areas outside the security zone where large protests and rallies are planned.

Security experts say the truck attack will heighten security concerns. But they note possible countermeasures, like establishing static, barricaded zones, can pose their own risk by creating targets.