VIDEO: Nice Attack Comes Amid Heightened U.S. Security Going Into Conventions

The truck attack that killed more than 80 people in Nice, France serves as an ominous reminder of the damage a lone terrorist can accomplish as the U.S. prepares for political conventions, reports USA Today .

Plowing a large vehicle through a crowd, as happened at the Bastille Day celebration in Nice, demonstrates the high level of damage that can be inflicted in open spaces that are difficult to defend against agile, one-person attacks.

The Nice mayor's office confirmed Friday that Mohamed Bouhlel, 31, a resident of the French seaside city, is the main suspect in the attack. Bouhlel, who was killed in a shootout with police, does not appear to have been known to intelligence services and was not on a terrorism watch list.

The Nice attack came as American federal authorities and big-city police departments heightened security after shooting attacks in Dallas, Orlando, and San Bernardino, and in the wake of Islamic State-linked bombings at airports in Istanbul and Brussels.

More than 3,000 federal security officials are heading to the Republican National Convention that starts Monday in Cleveland and the Democratic National Convention the following week in Philadelphia.

Thousands of state and local officers will also patrol the conventions. Extra steps for the convention include Cleveland police staffing two officers in each patrol car rather than one. Visible security measures in place for months at public events include searches of bags, more teams of bomb-sniffing dogs circulating and more screening equipment, according to the Department of Homeland Security.

But while federal and local authorities are monitoring security conditions, they say there are no specific threats against the conventions or big cities.

Brian Michael Jenkins, director of the Mineta Transportation Institute's National Transportation Safety and Security Center, said the policy debate is over how strictly to block or screen vehicles, while still allowing commerce and traffic to flow.

"The problem with a vehicle as weapon is that it's so accessible – you don't have to acquire an arsenal or build a bomb," Jenkins said. "It is a vulnerability of modern society."