Turkish media reports have quoted Prime Minister Binali Yildirim as telling a group of journalists on Sunday that Turkey aims to create a 30-kilometre deep "secure zone" in Afrin.
Earlier this week, the Turkish government announced the offensive into Kurdish-held areas in northern Syria, starting with Afrin, after reports that the USA plans to create a 30,000-strong border army predominantly made up of Kurdish militias.
The Kurdish Democratic Union Party, or PYD, the political arm of the SDF, said that, should Turkey launch its operation against Afrin, the world will bear responsibility for the lives of the people in the enclave.
Syria has warned against an incursion, threatening to shoot down Turkish jets.
Form for signing up for free newsletter. "We can protect our own borders", calling the fighters marauders.
The U.S. -led coalition declined to comment on Erdogan's threats.
"The global coalition and its partners remain united and committed to the lasting defeat of Daesh and to preventing its exportation of terror around the world".
Rather, he said, the USA military will provide training to local elements to help secure areas that were liberated from Daesh, with U.S. assistance, over the past three years.
The United States heads an global coalition that provided air support and special forces troops to aid the SDF in pushing IS out of its strongholds in northern and eastern Syria past year, including its self-proclaimed capital of Raqqa.
U.S. officials mis-spoke about a plan to set up a 30,000-strong militia in eastern Syria and owe angry ally Turkey an explanation, Secretary of State Rex Tillerson admits. The SDF now controls almost 25 percent of Syrian territory in the north and east.
The Turkish military said it had hit 153 targets so far, including shelters and hideouts used by Kurdish militants.
In a surprise development, Turkey's army chief General Hulusi Akar and spy chief Hakan Fidan were in Moscow on Thursday for talks with Russian counterparts on security issues and Syria, the army said in a statement.
"Our priority is the fight against terrorism", Parly said.
But the YPG has been the key ally of Turkey's fellow North Atlantic Treaty Organisation member the United States in the fight against IS jihadists, playing a key role in pushing the extremists out of their Syrian strongholds.
A Turkish military tanks arrives at an army base in the border town of Reyhanli near the Turkish-Syrian border in Hatay province, Turkey January 17, 2018.
The army emphasised that IS was also being targeted in this operation although it no longer has any major presence in the Afrin area.
A Reuters cameraman filmed Turkish artillery at the border village of Sugedigi firing shells on Friday morning into the Afrin region in northwest Syria.
"Don't stand between us and these herd of murderers".
"We will intervene in Afrin". "Tear off the insignia you have placed on the uniforms of the terrorists so that we don't have to bury them (U.S. soldiers) together with the terrorists".