U.S. President Donald Trump announced in October last year his decision to withdraw U.S. troops from northern Syria, ahead of a Turkish incursion into Kurdish-controlled northeastern provinces of the country.

Turkey sees the mainly Kurdish Syrian Democratic Forces (SDF) as an extension of the outlawed Kurdistan Workers Party (PKK), which has been fighting inside Turkey since 1984.

The SDF has provided the main bulk of ground forces of the U.S.-led coalition fighting against Islamic State in Syria. Nowadays, around 500 American soldiers still work with the SDF to protect oil fields in northeast Syria.

“We're back to see the situation four months later, and it's clear what was a delicate situation has become even more complex -- the U.S. position more tenuous than ever,” an ABC News correspondent said.

“We stood on the roof of an abandoned house along the stretch of land Turkey now occupies. Syrian regime flags all around us, Turkish forces sitting to our north, Russian convoys sweeping past and on a roundabout up the road, U.S. military vehicles sitting silently,” he said.

Reporter’s code: 50101