WASHINGTON — The F.B.I. has significantly increased its use of stings in terrorism cases, employing agents and informants to pose as jihadists, bomb makers, gun dealers or online “friends” in hundreds of investigations into Americans suspected of supporting the Islamic State, records and interviews show.
Undercover operations, once seen as a last resort, are now used in about two of every three prosecutions involving people suspected of supporting the Islamic State, a sharp rise in the span of just two years, according to a New York Times analysis. Charges have been brought against nearly 90 Americans believed to be linked to the group.
The increase in the number of these secret operations, which put operatives in the middle of purported plots, has come with little public or congressional scrutiny, and the stings rely on F.B.I. guidelines that predate the rise of the Islamic State.
While F.B.I. officials say they are careful to avoid illegally entrapping suspects, their undercover operatives are far from bystanders. In recent investigations from Florida to California, agents have helped people suspected of being extremists acquire weapons, scope out bombing targets and find the best routes to Syria to join the Islamic State, records show.
Officials said in interviews that because social media had given extremists a cloak of anonymity, these undercover stings — online and in person — had become increasingly vital to gathering evidence and deterring possible attacks in the United States.
“We’re not going to wait for the person to mobilize on his own time line,” said Michael B. Steinbach, who leads the F.B.I.’s national security branch. He added that the F.B.I. could not afford to “just sit and wait knowing the individual is actively plotting.”
Counterterrorism officials said the Islamic State had inspired loyalists to strike quickly, even within days or weeks of their radicalization. Unlike wiretaps or searches, undercover operations do not require a judge to sign a warrant. They are overseen by F.B.I. supervisors and Justice Department prosecutors, and so can usually be started more quickly.
But defense lawyers, Muslim leaders and civil liberties advocates say that F.B.I. operatives coax suspects into saying and doing things that they might not otherwise do — the essence of entrapment.
“They’re manufacturing terrorism cases,” said Michael German, a former undercover agent with the F.B.I. who researches national security law at New York University’s Brennan Center for Justice. In many of the recent prosecutions, he said, “these people are five steps away from being a danger to the United States.”
Karen J. Greenberg, the director of the Center on National Security at Fordham University, said undercover operations had become the norm for the F.B.I. in the most recent Islamic State cases, with little debate or understanding of how the bureau actually conducts its investigations, especially its online stings.
“I think the F.B.I. is really going down the wrong path with a lot of these ISIS cases,” she said, using a common acronym for the Islamic State, also known as ISIL.
Aggressive Methods
Court records and interviews give a glimpse of the aggressive undercover methods that have become typical in investigations once the F.B.I. identifies someone as a possible threat.
In Rochester, a paid informant went undercover and drove a man suspected of being an Islamic extremist, Emanuel Lutchman, to a Walmart in December to buy a machete, ski masks, zip ties and other supplies for a would-be terrorist attack on New Year’s Eve. Because Mr. Lutchman, a mentally ill panhandler, had no money, the informant covered the $40 cost.
In North Carolina, an undercover agent pressed another suspect, Justin Sullivan, on whether he was willing to commit acts of terrorism for the Islamic State — “do you think you can kill?” the agent asked in one online message — before giving him a silencer for an AR-15 assault rifle in June 2015.
And in Washington State, an undercover informant paid $1,100 to Daniel Franey, a former soldier, for acting as a lookout on several trips to buy duffel bags filled with assault weapons for a possible attack last summer.
The F.B.I. arrested all three suspects before any attacks occurred, and has used similar undercover techniques to prosecute dozens of others it believes had ties to the Islamic State, court records show. While some defendants have pleaded guilty, most are still awaiting trial.
At least 40 agencies use covert operatives to investigate everything from tax cheating and welfare fraud to Supreme Court demonstrations. But in no agency have undercover stings been more central than in the F.B.I.
While the F.B.I.’s internal guidelines, last updated in 2011, require the “least intrusive” methods possible in investigations, bureau officials said they believed less intrusive methods might be impossible because suspects have the ability to remain anonymous on encrypted online sites.