US President Donald Trump has told Australia and other anti-Islamic State coalition members the terror group's caliphate in Syria and Iraq will be erased in the coming week.
His bold declaration came as he addressed representatives from Australia and more than 70 other nations forming the global coalition fighting IS.
"It should be formally announced sometime, probably next week, that we will have 100 per cent of the caliphate," Trump told the gathering at the State Department in Washington DC on Wednesday.
"But I want to wait for the official word.
"I don't want to say it too early."
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Anthony Sheehan, deputy secretary of Australia's Department of Foreign Affairs and Trade, led Australia's delegation to the meeting.
US officials have said IS has lost 99.5 per cent of its territory in the region and holds on to less than five square kilometres in Syria near the Middle Euphrates River Valley.
Mr Trump described how he gave the go ahead to wipe out the remaining remnants of IS when he made a surprise visit to Iraq last month and spoke to one of his generals.
"I said 'Go at it. How long will it take once you get started?'," Trump said.
"He said, 'Sir, one week'.
"I said, 'Where did that come from? One week?'
"He meant it and it is about one week since they really got going and they'll be informing us very soon officially that it is 100 per cent."
Trump, who regularly went off his prepared speech during Wednesday's address, said there would always be "sick" and "demented" IS members and a "remnant can be very dangerous".
"We'll search them out, you'll search them out and we'll find them and hopefully they won't be around very long," Trump said.
Trump has vowed to pull US troops out of Syria and Iraq, but he said American forces would continue to work with coalition members until IS gets "smaller, smaller and smaller".
"Our military has been incredible and your militaries have been incredible so it is an honour to work with you and we will be working with you for many years to come," he said.
"I say that unfortunately, but that's the way it goes.
"We will work together for many years to come."
