Donald Trump’s top diplomat is hosting ministers from 68 countries to discuss a secret plan to confront and defeat Isis.

Secretary of State Rex Tillerson welcomed the foreign ministers to Washington, the first such gathering of the US-led military coalition since the election of President Trump in November. Mr Trump vowed that the fight against Isis would become a major priority for his government, and earlier this year he asked the Pentagon and other agencies to provide plans for defeating the militant group.

Addressing the meeting, Mr Tillerson called for new ideas to expand the fight against Isis in the Iraqi city of Mosul and accelerate the campaign to chase militants from Raqqa, Syria, while preparing for the complex humanitarian and political consequences of both efforts.

Yet Mr Tillerson did not propose, at least in his public remarks, a new approach, beyond noting the increased US military role in each country. “I recognise there are many pressing challenges in the Middle East, but defeating Isis is the United States number one goal in the region,” Mr Tillerson said. “As we've said before, when everything is a priority, nothing is a priority. We must continue to keep our focus on the most urgent matter at hand.”

Nothing Mr Tillerson outlined departed significantly from the Obama administration's strategy, which focused on using local forces to retake territory along with efforts to disrupt Isis recruitment and financing, and the blueprint of the multilateral effort seemed unchanged.

The meeting came after a US-led coalition aircraft dropped fighters for the first time into an area near the Syrian city of Raqqa to retake territory from Isis in a mission that included Apache helicopters, US Marine artillery and special operations troops.

The air drop of Syrian Democratic Forces, a militia alliance including Arab and Kurdish fighters, took place near the town of Tabqa in northern Syria, spokesman Colonel Joseph Scrocca said in a Pentagon news conference.

About 75 to 80 per cent of the forces were members of the Syrian Arab Coalition in the alliance, and the rest were from Syrian Democratic Forces, some of whom were Kurdish fighters, he said.

The Syrian Democratic Forces, which also includes the powerful Kurdish YPG militia, is fighting to encircle Raqqa city with support from the US-led coalition.

Mr Scrocca said it could be several weeks before the city of Tabqa, the Tabqa dam, and a nearby air field would be retaken from Isis.

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Iraqi Prime Minister Haider al-Ababi said victory was finally within reach.

“We are at the stage of completely decimating Daesh,” Mr Abadi said, using the Arabic acronym for Isis.

Mr Abadi had previously met with Mr Trump in Washington on Monday, said he had won assurances of more US support in the war against Isis.