The military operation in Northern Syria continues to press ahead despite warnings from Washington that the White House could sanction Ankara for the offensive against the US-backed Syrian Democratic Forces (SDF).

Turkish forces continue to press forward with a ground offensive against Kurdish militants, named "Operation Peace Spring", for a fourth straight day, advancing into northern Syria. Ankara plans to create a safe zone and peace corridor in the region, to the east of the Euphrates.

The Turkish authorities previously agreed on the issue with the United States, but later accused Washington of stalling the negotiations and vowed to create a safe zone without help from their allies, if necessary.

The contradictions between the two NATO countries resulted in the US withdrawing from several outposts and ignoring the operation. US Defence Secretary Mark Esper "strongly encouraged" Turkey to stop the offensive, stressing it is destabilising the region and warning of "serious consequences".

Damascus, in turn, has decried the deal between Turkey and the United States, calling both occupants, as they are operating in Syria without permission from its government. It also stressed that the operation may lead to the resurgence of ISIS in the country.

Turkish President Recep Tayyip Erdogan announced the launch of "Operation Peace Spring" in northeastern Syria on Wednesday. The offensive aims to force the predominantly-Kurdish Syrian Democratic Forces and the remaining Daesh militants out of the region.

According to Ankara, the op was launched under Article 51 of the UN Charter and UN Security Council Resolutions regarding the fight against terrorism. Turkey considers US-backed Kurdish troops as part of the Kurdistan Workers' Party (PKK) that Ankara has labelled as a terror group.