Counterterrorism officials are ramping up their concerns about the ability of foreign extremists to turn Americans into terrorists via the Internet.

The attack at a “Draw Mohammed” event in Garland, Texas, one month ago “exemplifies the call to arms approach employed by ISIL, along with the power of viral messaging,” Michael Steinbach, the FBI’s top counterterrorism official, told members of Congress on Wednesday. ISIL is an alternate acronym for the Islamic State in Iraq and Syria (ISIS). 

{mosads}“Social media is yet the latest tool exploited by terrorists,” he added.

For months, Obama administration officials have been warning about how foreign terrorist groups are able to inspire Americans, Europeans and others in the West to turn violent against their home country.

While ISIS itself has shown relatively little interest in launching attacks in the U.S., the group has had extraordinary success attracting foreigners to join their cause in Syria and Iraq.

The group’s social media prowess — which includes the use of slick marketing and the sophisticated ability to latch onto trending topics — has also helped direct foreigners to launch “lone wolf” attacks from thousands of miles away.

Ahead of the May Texas attack, for instance, an ISIS supporter posted a link to an article with information about the event, in which people were asked to draw the Prophet Mohammed. Muslims consider depictions of Mohammed deeply offensive.

One of the Americans involved in that Texas attack then reached out to the ISIS supporter and appeared to advertise their violence mere hours before the attack, using the hashtag “#TexasAttack.”

“This event highlights the growing threat our nation faces from a new generation of terrorist, often operating from afar, who use social media to find like-minded individuals within our borders,” deputy director of the National Counterterrorism Center, John Mulligan, said during the Wednesday hearing in the House Homeland Security Committee.

A security officer was wounded and both gunmen were killed in that attack last month.

The chairman of the Homeland Security Committee, Rep. Michael McCaul (R-Texas), raised additional alarms on Wednesday about the fatal Tuesday morning shooting of a man wielding a knife in Boston, who may have had connections to ISIS.

Later on Tuesday, another man was arrested in connection with that shooting, following what is reported to be a long-running terror investigation.

That incident is a “reminder of the dangers” facing the country, McCaul said.

Some reports have indicated that the victim of the Tuesday shooting, 26-year-old Usaama Rahim, had been radicalized by ISIS-affiliated social media accounts and had been making online threats to police.

“We know that a lot of their commands and calls to arms are an attempt to attack law enforcement and police officers,” McCaul said.