Turkish President Recep Tayyip Erdogan has rejected a US call for an immediate ceasefire in northern Syria.
Mr Erdogan’s comments come ahead of a visit to Turkey by the US vice-president Mike Pence and US secretary of state Mike Pompeo.
Erdogan Turkey launched an offensive designed to drive away Kurdish troops after their main ally, the US, pulled out.
Russia, which backs Syria, has said it prevent clashes between Turkish and Syrian forces which have now moved into the area after a deal with the Kurds.
Turkey considers elements of the Kurdish-led Syrian Democratic Forces (SDF) a terrorist organisation and want to push them away from the border area.
Ankara also says it wants to create a “safe zone” reaching about 30km (20 miles) into Syria to resettle up to two million Syrian refugees currently in Turkey.
However, Syrian forces – which are backed by Russia – advanced north at the weekend following a deal with the Kurds to try to hold back the Turkish operation.
Critics of the Trump administration say the withdrawal of US troops from the region 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.
Dozens of civilians have been killed in the operation so far and at least 160,000 have fled the area, according to the UN.
On Tuesday, 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”.