The weapon of choice lately for terrorists has been the automobile.

And, as investigators piece together the latest attack in Spain where 14 people died, terrorism investigators in the Pacific Northwest are keeping a close eye on the trend.

“We monitor those (events) around the world on a very regular, daily, hourly basis,” said Sgt. Jason Houck of the King County Sheriff’s Office.

At least three major incidents occurred in Europe before Thursday's carnage in Spain. At a rally in Charlottesville a white supremacist is accused of ramming his car through a crowd of counter-protestors killing one woman.

Houck says the office’s Joint Transit Anti-Terrorism Team has been analyzing the threat posed by terrorists who drive cars or trucks into crowds, inflicting mass casualties.

The Sheriff’s Office is responsible for security on Metro buses and light rail systems, which have been targets of attacks in other countries.

While Houck and the Seattle Police Department declined to provide specifics, local police say they are adjusting their terror fighting strategies to this new threat.

“The term for it in the intelligence community is ‘vehicle as weapon attack,’” said Malcolm Nance, a terrorism analyst for NBC News.

Nance says it appears to have evolved as one of ISIS’s most simple forms of attack.