“He acknowledged the truth, he gives [allegiance], the order has been given, his heart beats, he accepts, butterflies kick in … The target is given, the anticipation is over, a sense of relief.”

With this stream-of-consciousness narrative, an ISIS fighter using the name of Abu Abdullah Britani posted this call May 10 on Twitter to would-be jihadis in the West. Don’t second-guess yourself, he cautioned, in messages translated by the SITE Intelligence Group. “Thoughts going through your head, how many will be killed, how will they react, but you snap out.”

This is the menacing but murky face of the “lone wolf” attackers that U.S. counterterrorism officials see as an emerging threat for the homeland. They’re disparate, confused, Internet-savvy, eager for self-promotion and hard to find. Their very anonymity is frightening, to the point that one Middle East expert worried aloud last week, after the still puzzling Chattanooga murders by Muhammad Youssef Abdulazeez, that America was “one attack away” from a national furor about the lone-wolf threat.

Terror, of course, is precisely what these Internet recruiters want to generate. But U.S. officials caution that the best response is calm, steady work by police and intelligence agencies – and a resilient public. “It’s a problem we’ll have for the foreseeable future,” says one official who deals closely with the problem. “The U.S. is much better off than other parts of the world, but we have a lower threshold [of pain].”

After the Chattanooga attack, administration from the top down warned that the problem doesn’t have quick or easy fixes. “This threat of lone wolves and small cells is hard to detect and prevent,” President Barack Obama told the Veterans of Foreign Wars in Pittsburgh Tuesday. He promised “to keep doing everything in our power” to protect the country. But officials admit that the best measures are the simplest – communities watching for signs that may predict violent behavior, and a public that doesn’t panic when attacks come.

FBI Director James Comey was frank this week in Salt Lake City about the “troubled souls” the online jihadis are trying to mobilize. “Their message is travel to the Caliphate, their so-called Islamic wonder world. Join us here in Iraq or Syria, and if you can’t travel, kill somebody where you are. Kill somebody in uniform, preferably in the military or law enforcement, but just kill somebody.”

Comey isn’t exaggerating. On May 24, an ISIS fighter calling himself Abu Awlaki tweeted: “I don’t understand my ikwa [brothers] in the west. How can u walk past a police officer without stabbing him?” Last week, a fighter named Sayfullah al-Yemani posted a call to African-Americans: “I know there are black brothers who are fighting eliminationism and racism and need help. I urge you to embrace Islam and give Ba’yah [oath of fealty].”

In these jihadi postings, the brutal call to war is mixed with fantasies that might be drawn from a video game. That’s one reason some U.S. counterterrorism experts such as Michael Leiter, the former head of the National Counterterrorism Center, don’t often use the phrase “lone wolves.” They prefer “lone offenders,” which doesn’t play into the jihadis’ self-dramatization.

What troubles U.S. officials is the problem Comey has described as “going dark.” He says the FBI can’t break the strong encryption that communications and IT companies are offering users. He told Congress this month that he doesn’t want greater surveillance authority, but rather technical help from IT companies to access encrypted information “to ensure that we can continue to obtain electronic information … to keep us safe.” This presumably means “back doors” for decryption, which many companies resist.

The new lone-wolf era will test America’s ability to balance security and civil liberties, hopefully more wisely than was the case in the overreaction after Sept. 11, 2001. It’s a delicate task. More attacks will drive new calls to crack down through surveillance and more aggressive policing – creating more jihadis.

The jihadis’ tech skills are undeniable. Nearly every day, the SITE Intelligence Group translates new postings offering tutorials on encryption, phishing, secure messaging and other tools. One techie has even created an ISIS version of the online game “Flappy Bird.”

Here’s a taunting message tweeted this month by a jihadi named Kacamack: “where you are with whatever tool you have at your disposal … Or is it that you are all just talk and no walk?”

The right response to these taunts, say U.S. officials, is to keep cool and avoid playing the terrorists’ game.