The US special representative for Syria engagement Ambassador James Jeffrey has said that Trump administration hopes that the US backed fight against Islamic State in its last foothold in northeastern Syria will end within months but American forces will remain to ensure the "enduring defeat" of the militant group.

He said the United States believes the way forward in Syria includes defeating Islamic State, reinvigorating the political process and winding down the long-running civil war.

Toward that end, he said, the United States hopes to see the formation of a committee before the end of the year to work on a new constitution for Syria as agreed by the leaders of Russia, Germany, France and Turkey during their meeting in Istanbul in October.