WASHINGTON: In April, John Booker was arrested for allegedly planning to carry out a suicide bombing at a military base in Kansas on behalf of the self-styled Islamic State (IS) group.

It turns out that undercover FBI operatives had been manipulating the 20-year-old for six months ─ helping him make a “martyrdom” video, providing him with a list of bomb-making materials and even building an explosive device for him, albeit an inert one.

Critics say the Federal Bureau of Investigation's growing army of undercover agents tasked with hunting down terror recruits on US soil sometimes unduly pressures young, impressionable people to plan and move forward with acts they may otherwise not have conceived on their own.

The FBI "may have created terrorists out of law-abiding citizens," Human Rights Watch has alleged.

In total, the FBI employs at least 15,000 undercover informants who are spread out over a wide span of probes, ranging from paedophilia to drugs to terror.

Often well paid and operating with immunity, an informant can sometimes go so far as to suggest targets or provide weapons to convince a suspected recruit he or she is for real.

"They need to be convinced that you are just like them," said Mubin Shaikh, a former Canadian counter-terrorism operative who has worked undercover, including in an operation that saw the so-called Toronto 18 prosecuted.

"You have to play along, you have to do what they tell you to do. Otherwise your whole operation is compromised." Shaikh, who recounted his experiences in the memoir 'Underground Jihadi: Inside the Toronto 18', said there are a number of tactics to find out whether someone is an extremist or potential extremist.

In one approach, Shaikh would ask the suspect whether he would be interested in attending a "(terror) training camp", with the phrasing kept vague.

"If I say the exact same thing to somebody else and he says 'yeah, I do wanna go and train them,' that's you getting caught, that's not entrapment," Shaikh said.

"If that suggestion is well within the operational doctrine of that group, that's not entrapment, it's like a dangle. You're hooking somebody ─ it's like fishing."

Focus on Islamic State

Undercover agents are now heavily focused on identifying sympathisers of the IS group that has overtaken large swathes of Syria and Iraq.

Earlier this month, FBI Director James Comey said counter-terrorism investigators had followed "dozens and dozens" of suspected militants around the United States this summer and disrupted "many" of them.

Shaikh, a Muslim himself, acknowledged that with the high visibility of violent extremists who claim they are acting in the name of Islam today, "the Muslim community is completely under siege".

"Now the trust is really ruined," he added.

The problem is that in some operations, undercover agents set traps that, at times, appear to force the hand of suspects in their sights.

The topic is the focus of "(T)ERROR", a documentary that debuted at this year's Sundance independent film festival.

The film, which scored a Break Out First Feature award at the festival, provides an unprecedented behind-the-scenes view of a counter-terrorism sting over a two-year period.

These cases are not without controversy.

In one, the so-called Fort Dix Five group of alleged extremist men were said to have plotted to stage an attack on the US military base of the same name in New Jersey.

Five of the original group of six were found guilty of conspiracy to commit murder and four got sentenced to life in prison, including three Albanian brothers.

Before their 2007 arrest, they were placed under surveillance for a year and half after they had recorded vacation video footage of themselves shooting weapons in the countryside while shouting "Allah-ho-Akbar".

Critics accuse the FBI of entrapment, saying FBI informants pushed the men to action.

Mahmoud Omar, an Egyptian-born informant in the case, maintains that the Dukas brothers are innocent. "I still don't know why the Dukas are in jail," he told The Intercept in June.

The FBI acknowledges that using informants in investigations "may involve an element of deception, intrusion into the privacy of individuals, or cooperation with persons whose reliability and motivation may be open to question."

However, the bureau is quick to add, the courts have recognised that the use of informants is "lawful and often essential".

In addition, the FBI says, "special care is taken to carefully evaluate and closely supervise their use so the rights of individuals under investigation are not infringed".

Terrorists or just losers?

More often than not, these allegedly radicalised Americans are just youths with low self-esteem who, online, find a reason to exist, observers say.

Take the example of Joshua Ryne Goldberg, a 20-year-old Jewish man living with his parents in Florida who had invented a second life on the internet where he presented himself as living in Australia and flooded social networks with pro-jihad messages.

He was arrested last month after allegedly distributing information about bomb-making techniques. He faces 20 years in prison.

In Virginia, teenager Ali Amin was sentenced to 11 years in prison for using social media to support IS. Amin, 17, is the first minor to be prosecuted by the United States in a terrorism support case.

Shaikh called his case "tragic". But "when you have those guys online, preaching the IS message, trying to indoctrinate people, trying to recruit people, getting them themselves to do something, shouldn't we do something about that?"

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