BRUSSELS, BELGIUM - NOVEMBER 22: A Belgian police officer talks to a driver as they block a road leading to the city center during an operation in Brussels, Belgium, 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)
