It can be difficult to divine the precise role that international terrorists play in this or that attack. For example, the person who killed four U.S. Marines and a sailor in Chattanooga, Tennessee, in July 2015 was "motivated by foreign terrorist organization propaganda,"
FBI Director James Comey said, though he added that it's hard to say which terrorist group motivated the killer.
It also can be hard to get precise information about some attacks, but it's clear the deadly tentacles of ISIS have spread quickly from the terrorist group's epicenter in Iraq and Syria to points around the globe.
Here's a look at terrorist attacks outside Iraq and Syria believed to have been inspired or conducted by ISIS or its regional affiliates, along with context about the known connections to ISIS:
October 20, 2014
-- Martin Rouleau-Couture
runs over two soldiers, killing one, outside a government office in Saint-Jean-sur-Richilieu, Quebec. Rouleau-Couture had converted to Islam and expressed support for ISIS online. He may have been responding to ISIS spokesman Abu Muhammad al-Adnani's call to arms, according to the Institute for the Study of War.
ISIS mentioned Rouleau-Couture in its English-language magazine Dabiq, claiming the attack resulted from Adnani's call. It also included a picture of Rouleau-Couture in the magazine. The attack is believed to have been inspired by ISIS.
October 22, 2014
-- Gunman Michael Zehaf-Bibeau opens fire
at Canada's National War Memorial and Parliament Hill in Ottawa, killing army reservist Cpl. Nathan Cirillo. Zehaf-Bibeau is killed by House of Commons Sergeant-at-Arms Kevin Vickers. Two others, including a security guard, are injured. ISIS mentioned Zehaf-Bibeau in Dabiq, claiming that the attack was the "direct result of (Adnani's) call to action," the Institute for the Study of War reported
. The attack is believed to have been inspired by ISIS.
October 23, 2014 --
A man with a hatchet attacks four police officers
in New York. Police said the attacker, a U.S. citizen named Zale Thompson, was self-radicalized. Thompson had searched online for information on beheadings, al Qaeda, ISIS and al Shabaab, according to police. ISIS mentioned Thompson
in Dabiq, according to the Institute for the Study of War. The attack is believed to have been inspired by ISIS.
May 3, 2015 --
Two men open fire outside a Prophet Mohammed cartoon contest
in a Dallas suburb. The gunmen, Elton Simpson and Nadir Soofi,
wound a security guard before police shoot and kill them. Simpson linked himself to ISIS in a tweet posted before the attack, according to a federal law enforcement source.
The keynote speaker at the event was right-wing Dutch politician Geert Wilders, who was on an al Qaeda hit list. At least one of the gunmen appeared to have been in contact with an ISIS operative in Syria via social media. ISIS claimed responsibility, describing the attackers as "soldiers of the caliphate,"
according to the Institute for the Study of War. The institute described the attack as "ISIS-inspired," and U.S. officials said the group probably was being "opportunistic" in claiming responsibility. The attack is believed to have been inspired by ISIS.
November 4, 2015 --
University of California, Merced, student Faisal Mohammad stabs four people
before being shot to death by police. Authorities initially said the attack was simply the work of a disgruntled student, but the FBI concluded four months later that Mohammad had looked at ISIS and other terrorist websites and propaganda before the attack. The agency concluded the attack appeared to be terror-inspired, but said "it may never be possible to definitively determine why he chose to attack people on the UC Merced campus." None of the stabbing victims died.
December 2, 2015 --
Tashfeen Malik and her husband, Syed Rizwan Farook, shoot 14 people to death
and injure 21 others at a gathering of local government health workers in San Bernardino, California. Malik and Farook are gunned down in a shootout with law enforcement.
Malik pledged allegiance to ISIS leader Abu Bakr al-Baghdadi on Facebook, three U.S. officials familiar with the investigation told CNN.
The husband-and-wife team had developed extremist views
as early as 2013, a time that predates the rise of ISIS, FBI Director Comey has said. And Farook tried to contact other terrorist groups, a senior law enforcement official said.
"Individuals inspired by the Islamic State of Iraq and al Sham (ISIS) and with links to al Qaeda conducted the terrorist attack," according to the Institute for the Study of War.
"This attack was the first al Qaeda- or ISIS-related in the U.S. by a skilled shooter team using both guns and explosives." The attack is believed to have been inspired by ISIS.