The Islamic State group is a “global threat” which will take a generation or more to defeat, Washington’s envoy for the US-led coalition fighting the jihadists said Wednesday.

Despite “strategic momentum” against IS — or Daesh as he called it — General John Allen conceded that the fight would continue for several years in a keynote speech to the US-Islamic World Forum in Doha, Qatar.

And he added that if IS was not defeated it could “wreak havoc on the progress of humanity.”

Get The Times of Israel's Daily Edition by email and never miss our top stories Free Sign Up

“This will be a long campaign,” he said.

“Defeating Daesh’s ideology will likely take a generation or more. But we can and we must rise to this challenge. In an age when we are more interconnected that at any other time in human history, Daesh is a global threat.”

In a wide-ranging speech, Allen added that IS also poses a new type of threat because of its “depravity.”

“As someone who has spent nearly four decades as a United States marine, I have come closer than many to the reality of inhumanity.

“But I have never seen before the kinds of depravity and brutality in this region that ISIL represents and, in fact, that ISIL celebrates,” he added, using an alternative acronym for IS.

Allen was speaking the day after attending talks in Paris with ministers from around 20 coalition countries.

The meeting followed the fall of the city of Ramadi, the capital of Iraq’s largest province Anbar, to IS. That loss has been described as the worst defeat for the coalition since it formed nearly a year ago.

US Pentagon chief Ashton Carter blamed Iraqi forces, saying there was “an issue with the will of the Iraqis to fight,” in comments that angered Baghdad.

Iraq on Tuesday pleaded for more global support in the fight against IS.

The loss of Ramadi in Iraq plus the ancient city of Palmyra in Syria has led some to question the effectiveness of the US-led coalition in recent weeks.

Allen said the coalition had achieved some gains against the extremists.

He noted that IS had been defeated in many places in Iraq and that it has “lost over 25 percent” of the populated territory it once held in the country.

Another area of coalition success, Allen claimed, was its ability to disrupt the group’s access to finance.

“We are sharing information to block their assets to the global financial system. We are uncovering their points of access in the region and abroad for financial support,” he said.

He said the coalition had gained valuable intelligence on the organisation’s financial enterprises, but admitted that “Daesh still maintains financial resources”.

These included extortion, looting, kidnapping for ransom, and human trafficking, said Allen.