Concerned over President Donald Trump s decision to fire FBI Director James Comey , the FBI reportedly opened an investigation into whether Trump was secretly working on behalf of Russia, according to a New York Times report published Friday night.

The bureau opened the counterintelligence inquiry days after Comey was ousted in May 2017, the Times reported, citing several people, including former law enforcement officials, familiar with the probe.

Investigators were specifically looking into whether Trumps firing of Comey posed a national security threat as well as whether it was an obstruction of justice, considering the FBIs broader investigation into Russias meddling in the 2016 presidential election.

Former law enforcement officials told the Times that the criminal aspect (whether Trump obstructed justice) and counterintelligence aspect (whether Trump was working covertly for Russia) of the investigation were combined into one inquiry because it would have been considered a national security threat if Trump had indeed ousted Comey to impede the Russia investigation.

According to the Times, Trump at least twice linked his decision to fire Comey with the Russia investigation, prompting counterintelligence officials to probe the presidents actions.

First, two days after Comeys dismissal, Trump told NBC News Lester Holt that he had this Russia thing in mind when he decided to fire the FBI director.

In fact, when I decided to just do it, I said to myself, I said: You know, this Russia thing with Trump and Russia is a made up story, its an excuse by the Democrats for having lost an election that they shouldve won, the president told Holt at the time.

Second, Trump reportedly drafted a letter to Comey , slamming him for refusing to say that he wasnt the focus of the Russia investigation.

Shortly after Comey was fired, special counsel Robert Mueller was appointed to oversee the broader investigation into Russia and the election. Its unclear if Mueller is still investigating the counterintelligence inquiry into Trump.