A North Carolina man has been sentenced to life in prison for planning mass murder in support of ISIS.  At a press conference after the sentencing, Keri Farley, the FBI's assistant special agent in charge of North Carolina, said "homegrown violent extremists" are becoming harder to stop.

Charlotte Observer:

"Identifying a terrorist before an attack happens is one of the most difficult challenges we face," Farley said during a press conference with Rose after Sullivan's sentencing. "It's harder than finding a needle in a haystack; it's like finding a needle in a stack of needles. But that's exactly what happened in this case." ...

Before sentencing Sullivan, U.S. District Judge Martin Reidinger said the planned massacre was similar to the 2016 attack in Orlando, Fla., where a lone gunman killed 49 people.

Sullivan is among the 126 people arrested in the United States over the last three years for ISIS-related acts or conspiracies, according to the Program on Extremism at George Washington University. As with Sullivan, 90 percent of those charged have been male. The average age is 27. Some 45 percent were arrested as they attempted to join ISIS fighters overseas. About 30 percent have been accused of plotting to carry out attacks on U.S. soil.

Seamus Hughes, deputy director of the extremism program, says nearly nine out of 10 of those arrested are either Americans or permanent legal residents. None of these defendants likely would have been affected by the Trump administration's controversial travel ban, which has been resurrected by the Supreme Court and temporarily bars most residents of Iran, Libya, Somalia, Sudan, Syria and Yemen from entering the country.

Hughes says while the travel ban has drawn more public debate, the "vast, vast majority" of domestic terrorism cases raises the question of "What is the major threat?"

"Based on the numbers, we should be looking at home-grown terrorists, not necessarily individuals coming from the outside in. Sullivan is typical. He was born and raised here," he said.

Those 1,000 investigations prove that there are a lot of "known wolf terrorists" in the U.S.  No doubt they are hard to keep track of and stop before they act to kill a lot of people.

So the metaphor of trying to find "a needle in a stack of needles" is not entirely accurate.  We know what to look for and whom to look at; it's a question of having the resources to devote to keeping tabs.

Great Britain, France, Belgium, Germany, and other E.U. countries have up to five times the number of ISIS supporters in their countries.  The problems they have had in interdicting and prevent terrorists from attacking wherever they choose are well documented.  This despite enormous state resources devoted to keeping track of them.

In the U.S., the FBI is operating shorthanded.  Agents have to pick and choose which ISIS sympathizers might be the most dangerous because they simply don't have the manpower to do a better job.  In the case of the North Carolina ISIS wannabe, they succeeded in stopping a mass-casualty attack.  But for every Justin Sullivan, there are a dozen or  more who are basically flying below the FBI's radar.