"We are leading a comprehensive international campaign to crush ISIS's claim of invincibility, to deny ISIS a geographic haven from which to hatch murder, eliminate ISIS's ability to operate externally and eradicate their ability to recruit and finance terrorist operations," Mattis said.
"We have retaken over 55 per cent of ISIS territory there in the core. Over four million people have been liberated. And not one inch of territory seized from ISIS has been recaptured by them," Mattis told a Pentagon news conference along with General Joseph Dunford, Chairman of the US Joint Chiefs of Staff.
"Collaboration among many nations' intelligence services continues to complicate and blunt ISIS operations even as ISIS continues to pursue and conduct attacks against the United States and our allies through centralise directed plots, also through inspired attacks," he said, giving an update to reporters on the progress in the fight against ISIS.
Mattis said from the Philippines to Europe and beyond, while ISIS remained dangerous, they were no longer carrying an air of strength.
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"In Afghanistan two weeks ago, President Ghani announced we had killed the leader of ISIS Khorasan plus approximately two-thirds of their strength been killed during very tough operations mostly in Nangarhar Province," he said.
In Libya, the coalition struck a significant ISIS presence there in January of this year, he said.
"Our attack against their concentrated strength was highly effective, and ISIS did not own any major territory any longer there. Elsewhere, too, there have been successes. But in Iraq and Syria lies the core area of ISIS - of a geographic caliphate," he said.
Noting that attacks in Istanbul, Paris and Brussels were planned and coordinated out of ISIS's so-called capital in Raqqa, attis said additional eminent threats to many nations require America to move with urgency against all strongholds still in their hands.
Dunford said the US-led coalition, had reduced ISIS-held territory, limited their freedom of movement, destroyed a great deal of their leadership, reduced the flow of foreign fighters into and from the region and diminished their financial resources.
"Perhaps most importantly, we've undermined the credibility of their narrative that there's a physical caliphate in Iraq and Syria," he said.
Dunford said coalition airstrikes and ground operations had struck approximately 2,600 ISIS-held gas and oil targets, 1500 tanker trucks.
"These losses have limited ISIS' ability to plan and direct external attacks, recruit foreign fighters, broadcast their narrative and fund their brand of terror," Dunford said.
He said the US' strategic approach was to cut the connectivity between ISIS affiliates and associates, specifically the foreign fighter flow, their illicit resources and their message.
"Our objective is to drive down ISIS's capability to a point where local forces, with tailored support from the international community, are able to provide security. We're doing this today in Libya, Somalia and Syria, Yemen and Afghanistan," he said.