"The coalition to defeat ISIS (IS) has retaken almost 100 percent of the territory once held by these killers in Iraq and Syria," Trump said in a speech at the World Economic Forum in Davos, Switzerland.

"There is still more fighting and work to be done and to consolidate our gains."

IS has been dealt a string of defeats across Iraq and Syria in recent months.

The US-led coalition said on Tuesday it had killed as many as 150 IS fighters in an operation in the middle Euphrates River Valley in Syria, where some remained entrenched.

It said the Syrian Democratic Forces, a US-backed Arab-Kurdish alliance fighting IS, had assisted in target observation prior to the strike.

Kurdish ground forces have played a critical role in defeating IS.

On Wednesday IS claimed responsibility for a deadly attack on Save the Children's office in east Afghanistan that left at least two people dead and 14 others wounded.

"We are committed to ensuring that Afghanistan never again becomes a safe haven for terrorists who want to commit mass murder to our civilian populations," Trump added in his speech.