Washington's top envoy for the U.S.-led coalition fighting the Islamic State (IS) group says the militants are a "global threat" and it will take a "generation or more" to defeat the IS ideology.
Retired U.S. General John Allen said in a speech at the U.S.-Islamic World Forum in Doha, Qatar, on June 3 that although the coalition had "strategic momentum" in its battle against IS fighters, "this will be a long campaign."
He added that if IS was not defeated the group could "wreak havoc on the progress of humanity."
Allen's talk came one day after he attended talks in Paris with ministers from some 20 members of the anti-IS coalition.
Despite IS's takeover last week of the capital of Anbar Province, Ramadi, Allen said the U.S.-led coalition had defeated IS militants in many places and they had "lost over 25 percent" of the territory they once held in Iraq.