(CNN) The man accused of killing eight people after driving a truck onto a New York bike path is a "soldier of the caliphate," the ISIS terror group said without providing evidence to back up its claim.

"One of the Islamic State soldiers in America attacked on Tuesday a number of crusaders on a street in New York City," the group's weekly al-Naba newspaper reported Thursday.

ISIS provided no evidence it had knowledge ahead of Tuesday's attack in Lower Manhattan or was involved in planning. ISIS did not claim direct responsibility, and the article did not give a name for the attacker.

Responding to the claim Friday morning in a series of tweets, President Donald Trump called the New York terrorism suspect a "Degenerate Animal" and said the US military had attacked ISIS "much harder" over the past two days.

"ISIS just claimed the Degenerate Animal who killed, and so badly wounded, the wonderful people on the West Side, was 'their soldier,' " he tweeted.

"Based on that, the Military has hit ISIS 'much harder' over the last two days. They will pay a big price for every attack on us!"

ISIS just claimed the Degenerate Animal who killed, and so badly wounded, the wonderful people on the West Side, was "their soldier." ..... — Donald J. Trump (@realDonaldTrump) November 3, 2017

...Based on that, the Military has hit ISIS "much harder" over the last two days. They will pay a big price for every attack on us! — Donald J. Trump (@realDonaldTrump) November 3, 2017

He doubled down on those comments while speaking to reporters Friday morning at the White House.

"What we are doing is every time we are attacked from this point forward, and it took place yesterday, we are hitting them 10 times harder," Trump said.

Earlier this week Trump had tweeted that suspect Sayfullo Habibullaevic Saipov should be executed.

"NYC terrorist was happy as he asked to hang ISIS flag in his hospital room. He killed 8 people, badly injured 12. SHOULD GET DEATH PENALTY!" the President tweeted Wednesday night.

But it was the first time the terror group had put such a claim in its newspaper before releasing it through its media wing, Amaq News agency, usually the first point of publication for claims of responsibility.

Suspect's link to ISIS

Suspect Saipov has told authorities that watching ISIS videos inspired him to carry out this week's attack and that he closely followed the terror group's playbook, according to a federal criminal complaint.

The 29-year-old Uzbek native was charged with providing material support to ISIS, violence and destruction of motor vehicles, said Joon H. Kim, acting US attorney for the Southern District of New York.

Saipov drove a rented truck down a bike path near the World Trade Center, crashed into a school bus and then jumped out, brandishing imitation firearms, officials said. New York police Officer Ryan Nash shot him in the abdomen, and he was taken into custody. More than a dozen people were also injured in Tuesday's attack.

An artist's sketch shows suspect Sayfullo Saipov making his first court appearance Wednesday.

He didn't enter a plea to the federal terror charges in his first court appearance Wednesday.

Saipov was so devoted to ISIS, he wanted to display the terror group's flag in his hospital room, documents show. He had about 90 videos and 3,800 images on a cell phone featuring ISIS propaganda, including video of a beheading, according to the criminal complaint.

No signs of radicalization

Those who crossed Saipov's path are trying to reconcile the man they met with the image of the one about whom they're now hearing.

Approached in the lobby of her Brooklyn apartment building, the suspect's mother-in-law, Nodira Agzomova, said she was in shock.

"I don't know what happened," she said.

Those who knew Saipov in Tashkent, Uzbekistan, and in at least three states where he had lived since coming to the United States in 2010 said they saw no warning signs of radicalization.

"He was happy that he was here, he had a family here, and he was a truck driver and his business was really good," said Makhina Kadirova, a childhood friend.

His neighbors described him as quiet and said his family didn't socialize often.

Concrete barriers on bike path

The Lower Manhattan bike path where the attack took place has reopened, CNN affiliate WPIX reported, as New York started installing concrete barriers to prevent something similar happening.

The work started Thursday as part of a statewide review of shared-use paths, according to the New York State Department of Transportation.

Fifty-seven barriers are being positioned diagonally along the path, leaving enough space for bicycles, but not for larger vehicles, CNN affiliate WABC reported.

I guess that's one way to stop trucks from getting onto the bike path... pic.twitter.com/A8sjq1kXzP — 🚲 Jeff Jenkins 🚲 (@jeffwjenkins) November 2, 2017

However, some local cyclists said they think the barriers are problematic.

"There's no way two bikes can pass each other there and the runners as well," New Yorker James Petty told WABC. "There's going to be accidents."

Similar concrete barriers were placed in Times Square in May after a man drove a car onto a crowded sidewalk there , killing a woman and injuring at least 22 people.

Besides work on the bike path barriers, there are other signs that life's daily routines have resumed for many in the city.