Obama: US stepping up drive to 'completely decapitate' IS

The United States has halted the course of the Islamic State group, President Barack Obama said in remarks broadcast Friday, calling for a stepped up drive to "completely decapitate" the militants' operations.

The ABC News interview was recorded Thursday at the White House, hours after the start of a major operation by Iraqi Kurdish forces, backed by US-led strikes, to drive IS out of the northern town of Sinjar.

"I don't think they're gaining strength," said Obama. "From the start, our goal has been first to contain, and we have contained them. They have not gained ground in Iraq."

"And in Syria - they'll come in, they'll leave. But you don't see this systematic march by [IS] across the terrain," he said.

Obama gave the interview before news broke of a US air strike in Syria targeting "Jihadi John", a masked British militant who appeared in a string of graphic execution videos.

Syria war

IS has seized large chunks of territory in Iraq and Syria, partly achieved from seizing rebel-held territory in eastern Syria in 2014 and undermanned northern Iraqi checkpoints in a lightening advance.

"What we have not yet been able to do is to completely decapitate their command and control structures. We've made some progress in trying to reduce the flow of foreign fighters," Obama said.

"Part of our goal has to be to recruit more effective Sunni partners in Iraq to really go on offence rather than simply engage in defense."

The president warned that regional strife will persist "until we get the Syria political situation resolved".

"Until Assad is no longer a lightning rod for Sunnis in Syria and that entire region is no longer a proxy war for Shia-Sunni conflict, we're going to continue to have problems," he said.

"I would distinguish between making sure that the place is perfect - that's not going to happen anytime soon -- with making sure that [IS] continues to shrink in its scope of operations until it no longer poses the kind of threat that it does."

'IS' days are numbered'

US Secretary of State John Kerry on Friday warned the Islamic State group its "days are numbered", following an US strike in Syria targeting British militant "Jihadi John".

"The coalition forces conducted an air strike targeting...Jihadi John," whose real name is Mohammed Emwazi, he said on a visit to Tunis.

"We are still assessing the results of this strike but the terrorists associated with Daesh [IS] need to know this: Your days are numbered and you will defeated," said Kerry, using the Arabic acronym for IS.

"There is no future, no path forward" for IS, the secretary of state said.

Iraqi forces are also readying to liberate Ramadi city from IS fighters after months of delays.

But IS-suspected bombings in Lebanon's capital Beirut on Thursday and in Baghdad on Friday have shown that IS are still capable of inflicting harm.