Deadly lone-wolf terror attacks are the new American norm, and law enforcement won’t be able to stop everyone plotting to kill, counterterror experts tell Heat Street.

“There’s no doubt in my mind there will be more attacks,” says Michael Downing, who oversees a 900-person, five-division team as the deputy chief and commanding officer of the Los Angeles Police Department’s Counterterrorism and Special Operations Bureau.

Last fall, the Federal Bureau of Investigation said it was probing 1,000 potentially active Islamic State militants, at least one in all 50 states, “and I’m sure there’s a lot we don’t know about,” Downing says.

Investigators’ actions are limited by legal restraints, increasingly sophisticated Internet encryption, and even political correctness, Downing says. “It’s tough,” he says, noting the trade-off between security and freedom. “As long as we want to have some semblance of freedom, you’re going to have these risks, because it’s very difficult to detect these lone wolves.”

Even when federal investigators respond to a tip and open a preliminary investigation, they have just 90 days to look into someone, says Fred Burton, chief security officer at global-intelligence firm Stratfor and a former counterterrorism agent with the U.S. State Department.

If federal investigators don’t find sufficiently compelling evidence of a suspect’s capability and intent to carry out an attack, FBI and Department of Justice guidelines don’t permit them to open a full investigation, Burton says.

It’s extraordinarily difficult for investigators to catch a terrorist who hasn’t mentioned his plot to anyone—especially with the sophisticated privacy and encryption technology Internet users can now employ.

“It’s a very tough job,” Burton says. “It’s not an exact science, and it’s been my experience that, without intelligence and without sources that you can work and operate who can tell you exactly what you’re up against, it’s very hard to determine whether or not a lone shooter, a lone person, has the capability or the intent.”

Yet political correctness has made members of the public think twice before coming forward. Downing says he’s certain that highly publicized cases where a tipster got it wrong—the infamous clock boy, for instance—have deterred people from calling law enforcement when they see something suspicious.

“But I think these cases show that nothing is too small. If the hair stands up on the back of your neck and you can articulate it, report it to law enforcement,” Downing says, pointing to LAPD’s reporting app, iWatchLA.

While American law enforcement has done a generally good job thwarting terrorists, Burton says, “there’s also an unrealistic expectation on behalf of the media and the public that the FBI is going to be able to stop every one of these attacks.”

“I’m sad to say this to folks struggling [with Orlando], but these new mass-casualty attacks are the new norm, and we’ll see more,” Burton says.

Jillian Kay Melchior writes for Heat Street and is a fellow for the Steamboat Institute and Independent Women’s Forum.