A woman lights a candle in the area of the explosion at the Maelbeek subway station in Brussels, Belgium.(JULIEN WARNAND / EPA)
Belgian soldiers gesture for vehicles to keep clear as they patrol near a Brussels court building where Paris terror suspect Salah Abdeslam was expected to appear.
(Peter Dejong / Associated Press)
A Belgian police officer and soldier guard a Brussels court building where Paris terror suspect Salah Abdeslam was expected to appear.
b(Peter Dejong / Associated Press)
A police officer stands guard outside the Council Chamber of Brussels during investigations into the Paris and Brussels terrorist attacks.(Kenzo Tribouillard / AFP/Getty Images)
A woman and children sit and mourn for the victims of the bombings at the Place de la Bourse in the center of Brussels.(Martin Meissner / Associated Press)
Hundreds gather at Place de la Bourse in Brussels to mourn on Wednesday evening.(Martin Meissner / Associated Press)
Brussels Airport workers and relatives pay tribute to the victims of Tuesday’s attacks.(Philippe Huguen / AFP/Getty Images)
Police leave after investigating a house Wednesday in the Anderlecht neighborhood in Brussels, one day after Tuesday’s deadly suicide attacks.(Peter Dejong / Associated Press)
Soldiers and police carry out checks at the Central Station in Brussels on Wednesday, a day after blasts hit the Belgian capital.(Patrik Stollarz / AFP/Getty Images)
Police carry out checks at the Central Station in Brussels on Wednesday.(Patrik Stollarz / AFP/Getty Images)
A woman writes messages in a tribute to the people killed and injured in terrorist attacks at Place de la Bourse in Brussels.(Yoan Valat / European Pressphoto Agency)
A man reacts as people gather to observe a minute of silence in memory of the victims of the Brussels airport and metro bombings, on the Place de la Bourse in central Brussels.(PATRIK STOLLARZ / AFP/Getty Images)
People gather in Brussels to pay tribute to the victims a day after deadly terrorist attacks struck the city.(Aurore Belot / AFP/Getty Images)
People gather around floral tributes, drawings, candles and notes in front of the Bourse of Brussels on Tuesday(AURORE BELOT / AFP/Getty Images)
A woman writes a message on the ground as people leave tributes at the Place de la Bourse following today’s attacks in Brussels, Belgium.(Carl Court / Getty Images)
A security camera photo released on March 22 by Belgian authorities shows three suspects in the attack at Brussels Airport.(AFP/Getty Images)
An unidentified traveler lies on the ground in a smoke-filled terminal after an explosion at Brussels Airport on Tuesday.(Ralph Usbeck / Associated Press)
Two women injured in the explosions at Brussels Airport sit amid shattered glass on Tuesday.(Ketevan Kardava / Georgian Public Broadcaster )
An injured man lies on the floor waiting for aid at Brussels Airport.(Ketevan Kardava / Associated Press)
Smoke fills the terminal at Brussels Airport, where a pair of explosions killed at least 11 people.(Ralph Usbeck / Associated Press)
Brussels commuters climb out of a Metro subway car after an explosion at the Maalbeek station. A series of coordinated explosions ripped through Brussels Airport and the Metro station with dozens killed.(AFP/Getty Images)
Police and rescue teams set up outside the Maelbeek Metro station in Brussels.(Martin Meissner / Associated Press)
Special police secure the Brussels city center as Belgium raised its terror alert to its highest level on Tuesday.(Martin Meissner / Associated Press)
A victim receives first aid from rescuers near Maelbeek metro station in Brussels after an explosion.(Emmanuel Dunand / AFP/Getty Images)
A man with bloodstains on his sweater leaves Brussels Airport following explosions.(Dirk Waem / AFP/Getty Images)
People stand near Brussels Airport after being evacuated.(Geert Vanden Wijngaert / Associated Press)
Passengers are evacuated from Brussels Airport after explosions.(John Thys / AFP/Getty Images)
Emergency rescue workers tend to an unidentified person at the site of an explosion at a metro station in Brussels, Belgium.(Associated Press)
Soldiers block the access to roads close to a metro station in Brussels after a series of apparently coordinated explosions in the city.(Philippe Huguen / AFP/Getty Images)
A victim is evacuated after a explosion in a main metro station in Brussels.(Virginia Mayo / Associated Press)
Passengers leave Brussels Airport after explosions prompted an evacuation.(Laurent Dubrule / European Pressphoto Agency)
A woman is evacuated in an ambulance after a explosion in a Brussels metro station Tuesday.(Virginia Mayo / Associated Press)
People are evacuated from Brussels Airport on Tuesday following explosions.(Dirk Waem / AFP/Getty Images)
A man is wounded after explosions in Brussels Airport on Tuesday.(Ketevan Kardava / Georgian Public Broadcaster)
A Belgian police vehicle drives past passengers who are evacuating the Brussels Airport.(Jonas Roosens / AFP/Getty Images)
People walk away from Brussels Airport on Tuesday after it was rocked by explosions.(Geert Vanden Wijngaert / Associated Press)
All flights were canceled at Brussels Airport after two explosions rocked the main hall.(AFP/Getty Images)
In December, a married couple who authorities said had been “self-radicalized” killed 14 people in San Bernardino in what has been described as the deadliest terrorist attack on U.S. soil since 9/11.
Authorities found that the couple had bomb-making equipment in the garage of their townhouse and that one of them had plotted an earlier terror attack.
Still, experts say the terror attack in San Bernardino pales in comparison to the Paris and Brussels attacks due to those cities’ much more sophisticated and vast terror networks.
Based on months of investigation by the FBI and local police, the San Bernardino shooters had little support and appeared to act on their own after reviewing terrorist literature online.
By contrast, the terrorist cells in Brussels and Paris had the support of a network of bomb makers, safe houses and weaponry.
“The big difference between here and Europe and what has made Europe so dangerous is they have a far larger number of returning foreign fighters from Syria, and they, more importantly, have a logistical support network in place,” said Jenkins, a senior advisor to the Rand Corp.’s president.
Salah Abdeslam, the main fugitive in the Paris attacks seized in Brussels four days ago, Jenkins said, was a logistics specialist. “These fighters come back home determined to carry out an attack. But they need a place to hide, someone to build bombs, someone to supply weapons—they need a network.”
“In U.S., by contrast, we are seeing very little connectivity. We are seeing a single individual or autonomous action. They don’t have a terrorist underground here to turn to logistically,” Jenkins said.
Islamic State, he said, is under pressure domestically but that does not mean the fight is over. Jenkins said the group will likely go underground, but the foreign fighters will either head to another region such as Libya or take the risk of returning home. He said that may mean more attacks as Isalmic State is pushed back.
“Some will return home disillusioned, but others will determine to seek revenge,” Jenkins said.
Brian Levin, a Cal State San Bernardino terrorism expert, said he would not rule out an attack on U.S. soil from Islamic State. But he noted that terrorists in the U.S. don’t have the vast support network that can build suicide vests and hide people, as in Europe.
“The risk in Europe is different but it doesn’t mean we don’t have a risk here,” Levin said. “We remain one of their top targets,” Levin said.
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