US to install observation posts on Syria-Turkey border: Mattis

The US military will install observation posts along Syria's northern border with Turkey to help minimise tensions between the Turks and Washington's Kurdish allies in the fight against the Islamic State group (IS), defense secretary Jim Mattis has said.

"We are putting in observation posts in several locations up along the... northern Syrian border," Mattis told reporters Wednesday.

He added that the goal was to ensure the Syrian Democratic Forces (SDF), which includes the Syrian Kurdish YPG militia, "are not drawn off that fight," so "that we can crush what's left of the geographic caliphate." "They will be very clearly marked locations day and night so that the Turks know where they're at," he added, noting that the decision was taken in close cooperation with Turkey.

The SDF announced on November 11 it would resume its offensive against IS after having previously called it off due to new tensions with Turkey, which had shelled its positions in northern Syria.

The violence caused embarrassment for the United States, which is a key partner of the SDF, while Turkey is a NATO member and strategic ally.

Syria's long-oppressed Kurdish minority has established a semi-autonomous region in the north of the country, which has been wracked by conflict since 2011.

Turkey refuses to recognise the territory on its border, fearing it will exacerbate separatist ambitions of Kurds in its own country.

Ankara has carried out two operations against Kurdish forces since 2016, the last against the border enclave of Afrin, which it seized in March and is now controlled by pro-Turkish Syrian rebels.