ANKARA - Kurdish civilians in northeastern Syria are planning to stage open-ended sit-ins in areas near the border with Turkey in response to a looming Turkish military operation, according to local activists and journalists.

Sitting in "huge tents", people of all ages have begun gathering in the towns of Ras al-Ain, Tal Abyad and Kobane.

"[They] want to stand as human shields to prevent a Turkish advance," said Arin Sheikhmous, an activist based in Qamishli, where hundreds also gathered outside a United Nations office to call for international action.

The gatherings on Monday came a day after the United States announced its decision to withdraw troops from the northeastern region.

Washington's move cleared the way for Ankara to launch its long-threatened offensive and left the Kurdish-led Syrian Democratic Forces (SDF) across the border at risk of being attacked by Turkey, which considers them as "terrorists".

Ankara is yet to reveal the exact scope of its planned incursion, but has long said it wants to create a so-called "safe zone" into neighbouring Syria's northeast region. It has previously suggested it would carry out operations east of the Euphrates River.

The SDF, which spearheaded the US-led campaign against ISIL, described Washington's withdrawal announcement as a "stab in the back" but promised to "defend our land at all costs".(FA)