A van has crashed into dozens of people in Barcelona's historic Las Ramblas district, local police said on Aug. 17. (Reuters)

Within hours of a vehicular attack in Barcelona that killed at least 13 and injured dozens of others on Thursday, President Trump called it “terror.”

Yet at a news conference three days after a similar episode in Charlottesville, where an alleged Nazi sympathizer drove a car into a crowd of counterprotesters, killing one and injuring 19, the president would not definitely assign the same label.

“Was this terrorism?” a journalist asked on Tuesday.

“Well, I think the driver of the car is a disgrace to himself, his family and this country,” Trump replied, “and that is — you can call it terrorism, you can call it murder, you can call it whatever you want.”

At the time of the news conference, the name and alleged ideology of the Charlottesville driver, James Alex Fields Jr., were known. At the time that Trump tweeted about Barcelona, details about the driver had not been released by police, though it is possible that the president was privy to more information than the public.

Islamic State supporters celebrated the Barcelona attack, but the group did not immediately claim responsibility, according to the SITE Intelligence Group, which monitors extremist activity. (It later did, after Trump had tweeted.)

Recall that Trump claimed on Tuesday that he likes to be cautious when commenting on a violent incident.

“Before I make a statement, I need the facts,” Trump said. “I don’t want to rush into a statement.”

While defending his initial reaction to the Charlottesville violence, President Trump on Aug. 15 said he wants "to know the facts" before making statements. Here are three times that he didn't. (Bastien Inzaurralde/The Washington Post)

By the time Trump tweeted on Thursday, Barcelona police had called the attack an act of terrorism. The president's language was consistent with that of other officials.

But Trump balked at following similar guidance on the Charlottesville attack. A day before the president's news conference, Attorney General Jeff Sessions had said in interview with ABC News that “it does meet the definition of domestic terrorism in our statute.” Even before that, Trump's national security adviser, H.R. McMaster, had used the terrorism label, as had other Republicans, such as Sen. Ted Cruz (Tex.).

Trump still has not called the Charlottesville attack terrorism. Instead, he has spread blame for the violence to “both sides” — white supremacists and counterprotesters.

The president has spent much of the week mired in controversy over his response to the deadly attack in Charlottesville. The speed with which he attached the terrorism label to what happened in Barcelona was striking, as a point of contrast, and probably won't help his effort to shake that criticism.