Security measures tightened following alleged ISIL threat on New York subway

NEW YORK, UNITED STATES - SEPTEMBER 25: New York City Police officers stand guard with K-9 dog at metro station after Iraqs prime minister al-Abadi's explanation about the alleged bomb attacks on New York City and Paris subway systems by the Islamic State of Iraq and the Levant (ISIL), in New York, United States on 25 September, 2014. (Photo by Cem Ozdel/Anadolu Agency/Getty Images)