Turkey has warned it may reopen the route for Syrian refugees to enter Europe if it does not get more international support for creating a safe zone in northern Syria.
President Recep Tayyip Erdogan called for “logistical support” to establish a safe zone in Syria's north-east.
“Either this happens, or we will be forced to open the gates,” he said.
Turkey is hosting more than 3.6 million Syrians who have fled the civil war. The US backs the “safe zone” plan.
But the plan is controversial, because Syrian Kurdish forces are wary of Turkey moving many Syrians into the north-east who are not originally from that area.
The ethnic Kurdish People's Protection Units (YPG), seen by Turkey as a terrorist group, do not want to make way for Turkish forces in that area.
The US military has backed the YPG against so-called Islamic State (IS) fighters, whose territory is now much diminished.
“Our goal is for at least one million of our Syrian brothers to return to the safe zone we will form along our 450km [280-mile] border,” Mr Erdogan said in a speech in Ankara.
“Give us logistical support and we can go and build housing at 30km depth in northern Syria.”
Exodus from Idlib
Turkey wants US forces to jointly patrol the safe zone, and Mr Erdogan said Turkey was “determined to set it up by the last week of September”.
Turkish officials also fear that heavy fighting in the north-western province of Idlib could push more refugees into Turkey.
Syrian…
