Ankara has criticised President Trump's decision to arm the YPG, as its links to the PKK means the weapons could be used against Turkey.
Turkey's President Recep Tayyip Erdogan is to meet his US counterpart Donald Trump on Tuesday. The meeting comes at an awkward time, and follows the US president's decision last week to arm the YPG, the Syrian affiliate of the PKK, which Ankara and Washington DC agree is a terrorist organisation.
Trump's approval of plans to supply arms to the YPG complicates the talks between the two NATO allies and partners in the fight against Daesh.
"If we are strategic allies we must take decisions as an alliance. If the alliance is to be overshadowed we'll have to sort things out for ourselves," Erdogan said on Sunday.
TRT World's Clinton Nagoor has more on Turkey's concerns at US support for the YPG.
Placing dynamite under relations
The decision to arm the YPG was "tantamount to placing dynamite under Turkey-USA relations," a senior Turkish official said ahead of the talks.
"Just as it was being said that relations [which were] seriously harmed during the Obama period are being repaired, Turkey moving apart from one of its biggest allies would be an extremely bad sign," the official said.
"It is a slander of the Obama administration. Unfortunately, now they have left the Syria and Iraq problem in Trump's lap," Erdogan said in China.
Erdogan is expected to tell Trump that backing the YPG to retake Arab territory in Syria held by Daesh will sow the seeds of future crises and that other forces in the region including Kurdish Iraqi leaders also oppose the YPG, the Turkish official said.
Turkish Prime Minister Binali Yildirim said after talks in London last week with US Defense Secretary Jim Mattis that Erdogan's meeting with Trump would provide the US an opportunity to "correct the mistake" of its support for the YPG.