Police operation in Brussels(01 of17)
Open Image ModalBRUSSELS, BELGIUM - NOVEMBER 22: Belgian police officers secure an area as a reported police intervention takes place around the Grand Place central square in Brussels on November 22, 2015. Brussels will remain at the highest possible alert level with schools and metros closed over a \'serious and imminent\' security threat in the wake of the Paris attacks. (Photo by Dursun Aydemir/Anadolu Agency/Getty Images) (credit:Anadolu Agency via Getty Images)
Belgium Paris Attacks(02 of17)
Open Image ModalPolice set up a barricade during an operation in the center of Brussels on Sunday, Nov. 22, 2015. Western leaders stepped up the rhetoric against the Islamic State group on Sunday as residents of the Belgian capital awoke to largely empty streets and the city entered its second day under the highest threat level. With a menace of Paris-style attacks against Brussels and a missing suspect in the deadly Nov. 13 attacks in France last spotted crossing into Belgium, the city kept subways and underground trams closed for a second day. (AP Photo/Virginia Mayo) (credit:ASSOCIATED PRESS)
BELGIUM-FRANCE-ATTACKS(03 of17)
Open Image ModalPolice stand guard on a security perimeter, as a reported police intervention takes place, in Brussels on November 22, 2015. Brussels will remain at the highest possible alert level with schools and metros closed over a \'serious and imminent\' security threat in the wake of the Paris attacks, the Belgian prime minister said. Belgian police have launched several operations linked to the \'terrorist threat\' facing Brussels, which is under a top security alert over fears of Paris-style attacks, a spokesman said. AFP PHOTO / EMMANUEL DUNANDAFP PHOTO / BELGA PHOTO / LAURIE DIEFFEMBACQ\n\n==BELGIUM OUT== (Photo credit should read LAURIE DIEFFEMBACQ/AFP/Getty Images) (credit:LAURIE DIEFFEMBACQ via Getty Images)
BELGIUM-FRANCE-ATTACKS(04 of17)
Open Image ModalPolicemen gather during an intervention in Brussels on November 22, 2015. Brussels will remain at the highest possible alert level with schools and metros closed over a \'serious and imminent\' security threat in the wake of the Paris attacks, the Belgian prime minister said. Belgian police have launched several operations linked to the \'terrorist threat\' facing Brussels, which is under a top security alert over fears of Paris-style attacks, a spokesman said. AFP PHOTO / EMMANUEL DUNANDAFP PHOTO / BELGA PHOTO / LAURIE DIEFFEMBACQ\n\n==BELGIUM OUT== (Photo credit should read LAURIE DIEFFEMBACQ/AFP/Getty Images) (credit:LAURIE DIEFFEMBACQ via Getty Images)
Belgium Paris Attacks(05 of17)
Open Image ModalPolice lead away a man during a raid in Brussels on Sunday, Nov. 22, 2015. Western leaders stepped up the rhetoric against the Islamic State group on Sunday as residents of the Belgian capital awoke to largely empty streets and the city entered its second day under the highest threat level. With a menace of Paris-style attacks against Brussels and a missing suspect in the deadly Nov. 13 attacks in France last spotted crossing into Belgium, the city kept subways and underground trams closed for a second day. (AP Photo/Geert Vanden Wijngaert) (credit:ASSOCIATED PRESS)
Belgium Paris Attacks(06 of17)
Open Image ModalPolice patrol during an operation in the center of Brussels on Sunday, Nov. 22, 2015. Western leaders stepped up the rhetoric against the Islamic State group on Sunday as residents of the Belgian capital awoke to largely empty streets and the city entered its second day under the highest threat level. With a menace of Paris-style attacks against Brussels and a missing suspect in the deadly Nov. 13 attacks in France last spotted crossing into Belgium, the city kept subways and underground trams closed for a second day. (AP Photo/Virginia Mayo) (credit:ASSOCIATED PRESS)
Belgium Paris Attacks(07 of17)
Open Image ModalPolice close streets near the Grand Place in Brussels on Sunday, Nov. 22, 2015. Western leaders stepped up the rhetoric against the Islamic State group on Sunday as residents of the Belgian capital awoke to largely empty streets and the city entered its second day under the highest threat level. With a menace of Paris-style attacks against Brussels and a missing suspect in the deadly Nov. 13 attacks in France last spotted crossing into Belgium, the city kept subways and underground trams closed for a second day. (AP Photo/Geert Vanden Wijngaert) (credit:Geert Vanden Wijngaert/AP)
Police operation in Brussels(08 of17)
Open Image ModalBRUSSELS, BELGIUM - NOVEMBER 22: A Belgian soldier stands guard in front of Radisson Blu Hotel as a reported police intervention takes place around the Grand Place central square in Brussels on November 22, 2015. Brussels will remain at the highest possible alert level with schools and metros closed over a \'serious and imminent\' security threat in the wake of the Paris attacks. (Photo by Dursun Aydemir/Anadolu Agency/Getty Images) (credit:Anadolu Agency via Getty Images)
BELGIUM-FRANCE-ATTACKS(09 of17)
Open Image ModalPolice set a security perimeter, as a reported police intervention takes place, in Brussels on November 22, 2015. Brussels will remain at the highest possible alert level with schools and metros closed over a \'serious and imminent\' security threat in the wake of the Paris attacks, the Belgian prime minister said. Belgian police have launched several operations linked to the \'terrorist threat\' facing Brussels, which is under a top security alert over fears of Paris-style attacks, a spokesman said. AFP PHOTO / EMMANUEL DUNAND (Photo credit should read EMMANUEL DUNAND/AFP/Getty Images) (credit:EMMANUEL DUNAND via Getty Images)
APTOPIX Belgium Paris Attacks(10 of17)
Open Image ModalA Belgian Army soldier patrols on a main boulevard in Brussels, Sunday, Nov. 22, 2015. Western leaders stepped up the rhetoric against the Islamic State group on Sunday as residents of the Belgian capital awoke to largely empty streets and the city entered its second day under the highest threat level. With a menace of Paris-style attacks against Brussels and a missing suspect in the deadly Nov. 13 attacks in France last spotted crossing into Belgium, the city kept subways and underground trams closed for a second day. (AP Photo/Geert Vanden Wijngaert) (credit:ASSOCIATED PRESS)
Belgium Paris Attacks(11 of17)
Open Image ModalBelgian Army soldiers patrol near Christmas huts in front of the old Brussels\' stock exchange on Sunday, Nov. 22, 2015. Western leaders stepped up the rhetoric against the Islamic State group on Sunday as residents of the Belgian capital awoke to largely empty streets and the city entered its second day under the highest threat level. With a menace of Paris-style attacks against Brussels and a missing suspect in the deadly Nov. 13 attacks in France last spotted crossing into Belgium, the city kept subways and underground trams closed. (AP Photo/Geert Vanden Wijngaert) (credit:ASSOCIATED PRESS)
Belgium Paris Attacks(12 of17)
Open Image ModalBelgian Army soldiers patrol near deserted terraces in the center of Brussels on Sunday, Nov. 22, 2015. Western leaders stepped up the rhetoric against the Islamic State group on Sunday as residents of the Belgian capital awoke to largely empty streets and the city entered its second day under the highest threat level. With a menace of Paris-style attacks against Brussels and a missing suspect in the deadly Nov. 13 attacks in France last spotted crossing into Belgium, the city kept subways and underground trams closed for a second day. (AP Photo/Geert Vanden Wijngaert) (credit:ASSOCIATED PRESS)
Belgium Paris Attacks(13 of17)
Open Image ModalTwo people cross a deserted street near the main train station in the center of Brussels on Sunday, Nov. 22, 2015. Western leaders stepped up the rhetoric against the Islamic State group on Sunday as residents of the Belgian capital awoke to largely empty streets and the city entered its second day under the highest threat level. With a menace of Paris-style attacks against Brussels and a missing suspect in the deadly Nov. 13 attacks in France last spotted crossing into Belgium, the city kept subways and underground trams closed for a second day. (AP Photo/Geert Vanden Wijngaert) (credit:ASSOCIATED PRESS)
Belgium Paris Attacks(14 of17)
Open Image ModalA Belgian Army soldier and policeman patrol near Christmas stalls in the center of Brussels on Sunday, Nov. 22, 2015. Western leaders stepped up the rhetoric against the Islamic State group on Sunday as residents of the Belgian capital awoke to largely empty streets and the city entered its second day under the highest threat level. With a menace of Paris-style attacks against Brussels and a missing suspect in the deadly Nov. 13 attacks in France last spotted crossing into Belgium, the city kept subways and underground trams closed for a second day. (AP Photo/Geert Vanden Wijngaert) (credit:ASSOCIATED PRESS)
Belgium Paris Attacks(15 of17)
Open Image ModalThe closed entrance to the metro at the main train station in the center of Brussels is closed on Sunday, Nov. 22, 2015. Western leaders stepped up the rhetoric against the Islamic State group on Sunday as residents of the Belgian capital awoke to largely empty streets and the city entered its second day under the highest threat level. With a menace of Paris-style attacks against Brussels and a missing suspect in the deadly Nov. 13 attacks in France last spotted crossing into Belgium, the city kept subways and underground trams closed for a second day. (AP Photo/Geert Vanden Wijngaert) (credit:ASSOCIATED PRESS)
BELGIUM-FRANCE-ATTACKS(16 of17)
Open Image ModalSoldiers stand guard in front of the central train station on November 22, 2015 in Brussels, as the Belgian capital remained on the highest security alert level over fears of a Paris-style attack. AFP PHOTO / Emmanuel Dunand (Photo credit should read EMMANUEL DUNAND/AFP/Getty Images) (credit:EMMANUEL DUNAND via Getty Images)
Police operation in Brussels(17 of17)
Open Image ModalBRUSSELS, BELGIUM - NOVEMBER 22: Belgian police officers and soldiers secure an area as a reported police intervention takes place around the Grand Place central square in Brussels on November 22, 2015. Brussels will remain at the highest possible alert level with schools and metros closed over a \'serious and imminent\' security threat in the wake of the Paris attacks. (Photo by Dursun Aydemir/Anadolu Agency/Getty Images) (credit:Anadolu Agency via Getty Images)