The 19-year-old man accused of attacking three NYPD officers with a machete near Times Square on New Year's Eve was motivated by Islamic extremism, police sources said Monday. 

Trevor Bickford, of Wells, Maine, faces two counts of attempted murder of a police officer and two counts of attempted assault in connection with Saturday night's attack, the NYPD said Monday afternoon.

The sources said Bickford, who recently converted to Islam, had planned to take part in attacks overseas, but ultimately traveled to the city instead.

Bickford had been on law enforcement officials’ radar since mid-December, when his family reported his alleged radicalization, according to the sources. He had a journal containing entries that made reference to the Muslim community, as well as his plan to die during the attack, the sources said.

According to law enforcement sources, he was on the FBI's watch list. Those sources said his family reported that he had expressed an interest in joining the Taliban.

NYPD Chief of Intelligence and Counterterrorism Thomas Galati said on “Mornings On 1” Tuesday that while Bickford was known to authorities in Maine, he was unknown to the NYPD prior to the attack.

“Not every police department can be notified on every single person. If there was some nexus to New York, then they would have notified,” Galati said.

He did, however, praise FBI authorities for their diligent work in ensuring Bickford could be easily identified.

“I think that they did what was prudent up in Maine. They went out, they interviewed the family – a couple of days later they interviewed him, they put a watch on him so that he cannot leave the country and fly out. They opened up a full investigation into him so they did everything they were supposed to do,” he said.

Galati also said that he believes Bickford fell victim to ISIS or al-Qaida propaganda, but there is no information to verify either terrorist organization was directing him. Galati expects Bickford to receive terrorism-related charges and noted that an investigation is ongoing.

“They're just putting propaganda out there and hoping that somebody's going to act on what they put out,” Galati said.

Galati said all three officers involved in the incident are recovering well after being released from Bellevue Hospital.

The NYPD said the attack happened around 10 p.m. Saturday night on Eighth Avenue near West 52nd Street, right outside the security zones for the Times Square ball drop.

In a radio interview on WABC Tuesday morning, Mayor Eric Adams praised the NYPD for a swift response that did not disrupt the New Year’s Eve festivities at Times Square.

"The officers immediately after controlling the situation continued to provide the services to hundreds of thousands of people," Adams said. "We saw just really why New York City is a professional police department bar none."

NYPD Commissioner Keechant Sewell, who held a news conference later that night with Adams and other high-ranking NYPD leadership, also praised officers, adding that Bickford approached an officer unprovoked and attempted to strike them in the head with machete.

After the attempted attack, the man then struck two other officers in the head with the machete, Sewell said.

The attack left one of the officers — an 8-year NYPD veteran — with a cut to the head, Sewell said. The second officer, who had just graduated from the Police Academy on Friday, suffered a skull fracture and a “large laceration,” the commissioner said.

One of the officers fired at Bickford, hitting him in the shoulder, police said. He was later taken into custody at the scene and treated at Bellevue.