Ankara: Recep Tayyip Erdogan on Monday promised he would stop a Kurd-led border force being created by the USinfo-icon, and said final preparations were under way to invade the Kurdish canton of Afrin, as tensions rose once again between the ostensible allies over Syriainfo-icon.

The US infuriated its NATO partner Turkeyinfo-icon on Sunday by announcing that Washington and a coalition of its allies purportedly fighting Daesh will work with US-backed militants of the so-called Syrian Democratic Forces (SDF) to set up a new 30,000-strong "border security" force.

The force would operate along the Turkish border with Iraqinfo-icon and within Syria along the Euphrates River.

Washington also said it is supplying weaponsinfo-icon and training to anti-Damascus militants of the Kurdish People's Protection Units (YPG), the SDF's main backbone. Turkey views the YPG as a terrorist group and the Syrian arm of the homegrown Kurdistan Workers' Party (PKK), which has been fighting for independence over the past decades.

The US had promised to take back the weapons from Kurdish militants once Daesh falls.

Reacting to the US military's announcement, Turkish President Recep Tayyip Erdogan said Washington is "building an armyinfo-icon of terror" on the border with Syria," and that "it is our responsibility to strangulate this effort before it is born."

"A country we call an ally is insisting on forming a terror army on our border," Erdogan said in a speech in Ankara. "What can that terror army target but Turkey? Our mission is to strangle it before it's even born."

"This is what we have to say to all our allies: don't get in between us and terrorist organisations, or we will not be responsible for the unwanted consequences," Erdogan said.

"Either you take off your flags on those terrorist organisations, or we will have to hand those flags over to you ...Our operations will continue until not a single terrorist remains along our borders, let alone 30,000 of them."

Erdogan also said that Turkey's armed forces had completed preparations for an operation against the Kurdish-controlled region of Afrin in northwest Syria. On Sunday, he told members of his AKP party: "If the terrorists in Afrin don't surrender, we will tear them down." 

Turkish Foreign Minister Mevlut Cavusoglu echoed Erdogan's remarks, urging the US to clarify its stance.

"The US must clarify which side it is on, whether it chooses to be with its allies or terror groups," he said, warning, "We will take our own measures [against terror groups] regardless of who backs them; whether it is the US or other countries, it doesn't matter to us."

In August 2016, Turkey began a unilateral military intervention in northern Syria, code-named Operation Euphrates Shield. Ankara said the campaign was aimed at pushing Daesh terrorists from Turkey's border with Syria and stopping the advance of Kurdish forces.

Turkey ended its Syria offensive in March 2017, but has kept its military presence there.

Syria has voiced strong opposition to both Turkish and American military actions on its soil, repeatedly calling on the two NATO allies to pull their forces out.

Washington's border force plan drew angry reactions from both Syria and Russiainfo-icon, with Damascus describing it as a "blatant assault" on its sovereignty.

Russia also said the US was seeking to split the Syrian territory.

"In fact, that means separation of a huge territory along the border with Turkey and Iraq," Foreign Minister Sergei Lavrov said. "The actions we currently see indicate that the United Statesinfo-icon does not want to keep the territorial integrity of Syria."

'US after dividing Syria' 

Meanwhile, Syrian Deputy Foreign Minister Faisal Mekdad on Monday denounced the US bid to form "an armed militia" as a desperate attempt to divide the country and prolong the crisis there.

He told Lebanoninfo-icon's Al Mayadeen television channel that the efforts by Washington and its agents in the Persian Gulfinfo-icon region as well as Turkey to undermine Syria's unity and sovereignty were in vain amid sweeping gains by the Syrian army and its allies against terrorists on the battlefield.

Mekdad also expressed confidence in the Syrian people's ability to foil the new conspiracy, adding that the presence of foreign forces on Syrian soil without coordination with the Damascus government is illegitimate.

Fawaz Gerges, a professor of International Relations at the London School of Economics, warned that for Turkey, the US-backed border force was a "slap in the face" and has inflamed tensions between the two countries.