A US Air Force AV-8B Harrier II returns from striking ISIS in Iraq
A US Air Force AV-8B Harrier II returns from striking ISIS in IraqReuters

The US-led fight against the Islamic State jihadist group in Iraq and Syria could be completed within 14 months, a senior US official told skeptical lawmakers Tuesday.

Some 65 countries are engaged at varying levels in trying to defeat the ISIS group in its so-called caliphate in Iraq and Syria, under a campaign that began in August 2014 and was initially devised to take three years.

US lawmakers, especially Republicans, have frequently blasted President Barack Obama for what they call an overly cautious approach that moves too slowly and only takes incremental steps in ramping up the fight.  

"We're not going to defeat them within 14 months, are we?" Senator Ron Johnson asked Brett McGurk, who is Obama's special envoy for the coalition.  

McGurk, speaking at a Senate Foreign Relations Committee hearing, pointed to progress in the 22-month-old operation and said he wanted it finished even before it hits the three-year mark.

"I want it to go a lot faster than that," he told senators.

"We are moving at a tempo that I believe will lead to the ultimate defeat" of ISIS, he added.

Within the past week, Iraqi security forces have recaptured Fallujah from the Sunni Islamists, and are looking to eventually seize Mosul.

In Syria, US-backed local fighters are focusing on the city of Manbij before an eventual battle for Raqqa, the de facto capital of ISIS's "Caliphate".

The Obama administration is struggling with how best to characterize the fight.

On the one hand, ISIS has lost large portions of land it once held and thousands of its fighters have been killed.

But John Brennan, the director of the CIA, last week warned that the jihadists' "terrorism capability and global reach" had not been reduced and the number of terror attacks claimed or inspired by the group overseas is still on the rise.

His comments came just days after a gunman who pledged allegiance to ISIS slaughtered 49 people in a Florida gay nightclub.

Still, McGurk told lawmakers that external financing for ISIS had been severed and said the jihadists' online propaganda was now being successfully countered by a global network of individuals, groups and companies.

He also said ISIS leaders were being killed at a rate of one every three days.

"And ISIL's territory is shrinking, losing nearly 50 percent of territory it once controlled in Iraq and 20 percent in Syria over the last 18 months," McGurk added, using another term for the jihadist terror group.

AFP contributed to this report.