Turkish President Recep Tayyip Erdogan has vowed to press on with an offensive in Syria until his mission to create a “safe zone” is complete.
Turkish forces launched an operation to clear Kurdish fighters from northern Syria last week, after US troops allied to them pulled out of the region.
The Turkish government views one of the main militias as a terrorist group.
Mr Erdogan has also said he will snub direct talks with the US vice-president when he arrives in Turkey.
The Turkish president said that Mike Pence and US Secretary of State Mike Pompeo would only speak to their counterparts and not him directly on Thursday.
“When Trump comes here, I’ll talk to him,” he said.
Turkey launched the offensive in northern Syria because they consider the dominant militia in the Syrian Democratic Forces (SDF) an extension of a banned group within Turkey.
The SDF alliance on Sunday announced a deal with the Syrian government for help to repel the Turkish assault.
What is the plan of Turkey for War?
In remarks on Wednesday, Mr Erdogan called on “terror organisations” in northern Syria to lay down their arms in order to end Turkey’s military operation.
“Our offer is that immediately tonight all terrorists should drop their weapons, equipment and everything, destroying their traps and leaving the safe zone we have designated,” he told a meeting of his Justice and Development Party’s (AKP) parliamentary group.
He also rejected calls, apparently from foreign leaders, to enter mediation with the group.
The Turkish government insists the People’s Protection Units (YPG), which dominate the SDF, are an extension of the Kurdistan Workers’ Party (PKK) – a group which has fought for Kurdish autonomy in Turkey for decades.
Mr Erdogan has maintained the offensive will only end when his planned “safe zone” is cleared of Turkish forces.
He wants the area to reach about 20 miles (32km) into Syria “stretching from Manbij to the Iraqi border” where up to two million Syrian refugees in Turkey can be resettled.
Critics of the Trump administration say the withdrawal of US troops from the region, shortly after a call with Mr Erdogan, gave Turkey a “green light” for the offensive.
The US has repeatedly denied this, and on Monday Washington announced sanctions on Turkish ministries and senior government officials.
Mr Pence and Mr Pompeo are due to travel to the Turkish capital, Ankara, on Thursday.
Mr Pence on Monday warned that the US sanctions against Turkey would worsen “unless and until Turkey embraces an immediate ceasefire” and negotiates a long-term settlement on the border.
US President Donald Trump has faced mounting pressure to take action against Turkey – a key Nato partner – including from Republicans usually loyal to his administration.
But on Tuesday Mr Erdogan maintained Turkey “will never declare a ceasefire” despite US calls.
“They are pressuring us to stop the operation. They are announcing sanctions. Our goal is clear. We are not worried about any sanctions,” the president added.
Russian President Vladimir Putin has also discussed the situation with Mr Erdogan in a phone call, a Kremlin spokesman said on Wednesday. Mr Erdogan had accepted an invitation to visit Russia for a working visit this month, the spokesman added.
Russia has vowed it will not allow clashes between Turkish and Syrian forces.
What’s the latest on the ground?
Dozens of civilians have reportedly been killed in Turkey’s operation so far and at least 160,000 have fled the area, according to the UN.
The medical charity Médecins Sans Frontières (MSF) said it had “taken the difficult decision to suspend the majority of its activities and evacuate all its international staff from north-east Syria”.
Syrian government forces on Tuesday entered the strategic town of Manbij, inside the area where Turkey wants to create its “safe zone”.
Meanwhile, Turkish troops and pro-Turkish, anti-government fighters had also been gathering near Manbij.
Over the past two years, hundreds of US troops have visibly patrolled the strategic town, but they left earlier this week.
On Tuesday, Russia – a key ally of Syrian President Bashar al-Assad – said its forces were patrolling along the “line of contact” between Syrian and Turkish forces.
For now, Syrian forces have not been deployed between Tal Abyad and Ras al-Ain, where Turkey has focused its efforts.
How did we get here?
Kurdish-led forces have been a key ally of the US in the fight against the Islamic State (IS) group in Syria.
They described the US withdrawal, which preceded Turkish action, as a “stab in the back”.
There are fears the destabilisation could lead to a resurgence of so-called Islamic State (IS), as thousands of former fighters and their relatives are being detained in northern Syria.
Hundreds of IS family members are said to have already escaped from one camp.
Analysts say that apart from fighting IS, the Kurds were fundamental to the US in limiting the influence of rivals Russia and Iran and keeping some leverage on the ground.