WASHINGTON — So-called lone-wolf terrorists can kill a lot of people at one time, and stopping them presents a nightmare for authorities.

The Obama administration has emphasized battling Islamic State terrorists in their stronghold in Iraq and Syria. But some recent attackers, perhaps including the one in France on Thursday night, have had minimal or no contact with the terror group’s hierarchy. They can be driven by factors other than ideology, including suicidal tendencies and deep alienation.

That means destruction of the Islamic State won’t necessarily diminish the occurrence of attacks. Some lone-wolf terrorists are motivated by other factors, including social alienation and mental instability.

“I do think we shouldn’t second guess the value of degrading the Islamic State in its stronghold,” said Max Abrahms, a political scientist and terrorism expert at Northeastern University in Boston. “The brand will suffer. They will have a more difficult time attracting recruits.”

At the same, he said, “Its capability goes down but its motivation for attack goes up.”

The attack along the French seaside promenade in Nice apparently was carried out by a lone Frenchman of Tunisian descent who used a truck as his main weapon.

“Lone wolf attackers can indeed be very bloody even in countries where access to guns is restricted, like in France,” said Abrahms, who described the Bastille Day massacre in Nice as “arguably the most lethal lone-wolf attack ever.”

In addition to killing 84 people, the 31-year-old truck driver, identified by French officials as Mohamed Lahouaiej Bouhlel, injured 200 other people, 54 of them critically.

The perpetrator had a background of petty crimes, and is not known to have had accomplices. Authorities pored over his background Friday in a search for terrorist ties and acknowledged he was on no terror watch lists.

The French attack came a little more than a month after American-born Omar Mateen, who was possibly inspired by Islamic State extremism, killed 49 people at a gay nightclub in Orlando, Florida, in the deadliest terror attack on U.S. soil since the Sept. 11 terror attacks in 2001. Mateen used a semi-automatic rifle and a pistol.

Lone-wolf killers often have criminal histories and suicidal tendencies, experts said.