"As the Paris attacks demonstrated, ISIL [Islamic State] has become the most significant terrorist threat [of] the United States and our allies," Stewart said. "ISIL will probably attempt to conduct additional attacks in Europe and attempt to direct attacks on [the] US homeland in 2016."
The US general explained that in 2015 Daesh was able to remain in the areas it controls in Syria and Iraq and moreover was able to "expand globally."
"ISIL’s foreign fighter cadre is core to its external attack capability, and a large number of western jihadists in Iraq and Syria will pose a challenge for western security services," Stewart said.
The United States and its allies of over 60 nations have been conducting a large-scale airstrike campaign against Daesh insurgents in Iraq and Syria since 2014, however, in Syria without the approval of the UN Security Council or the Syrian government.