Last week US President Donald Trump authorised the Pentagon to equip "Kurdish elements" of the US-backed Syrian Democratic Forces (SDF), which the YPG dominates, in a bid "to ensure a clear victory" over Daesh in Raqqa, Syria.
The Turkish Government considers the YPG to be an integral part of the Kurdish Workers' Party (PKK), which both the USA and Turkey designate a terrorist organization.
It was unclear whether Erdogan would be mollified by US offers to compensate for Ankara's acceptance of the YPG role in the battle for Raqqa.
United States forces are seen at YPG headquarters after it was hit by Turkish air strikes in Mount Karachok, Syria. First, enhanced and increased US assistance against the PKK, without any public expressions of concern about the tactics the Turkish military uses in civilian areas of southeastern Turkey. In a way, Putin was sending a public message to Trump before Erdoğan arrives in the U.S.to not leave any door open for Erdoğan regarding the YPG which could be used as a bargaining chip regarding Trump's Syria policy - something that Erdoğan said he hopes to change.
Also hanging over the meeting will be Trump's business interests in Turkey.
On Monday, German Chancellor Angela Merkel said that Germany could move its 250 troops from Turkey's Incirlik air base to an alternative base in Jordan after Turkey did not allow German lawmakers to visit the base.More news: Aust hangs back on China Silk Road plan
The fall of Tabqa, some 40 kilometers west of Raqqa, leaves no other major urban settlements on the road to the militant group's self-proclaimed capital and base of operations in Syria.
Trump's deal-making skills will be put to the test as he tries to assure Erdogan that weapons won't fall into the wrong hands. Bozdag reportedly told U.S. Attorney General Jeff Sessions that Turkey would no longer respond to U.S. extradition requests if the administration regarded evidence against Gulen presented by Turkey as insufficient. However, the USA authorities did not find in the multi-volume cases submitted by Ankara any confirmation of the famous preacher's participation in Turkey's attempted military coup last summer. "The media and press freedoms have been placed under government control".
Trump and Erdogan have spoken at least three times, and in two of those conversations they discussed plans to fight ISIS in Syria, according to the White House.
He will undoubtedly ask for his Turkish rival, Fethullah Gulen, living in Pennsylvania, to be turned over. Those include extraditing the Pennsylvania-based cleric, Fethullah Gulen, whom Erdogan blames for fomenting a failed coup last summer, and dropping US charges against Reza Zarrab, a Turkish businessman accused of money-laundering and violating USA sanctions in Iran.
"Turkey is under a state of emergency since (the failed coup), during which human rights have been trampled on", said Sezgin Tanrikulu, a legislator from Turkey's main opposition Republican People's Party, or CHP. Our only hope is that Erdoğan makes it up with Trump by then. In a 2015 interview with Breitbart's Steve Bannon - now a White House adviser - the president admitted: "I have a little conflict of interest because I have a major, major building in Istanbul", adding that the tower there was "a tremendously successful job". "It's called Trump Towers - two towers, instead of one, not the usual one, it's two".
"We do have a relationship with the people who administer the talks, but there is no advance in our attendance..."
Boosting the commercial relationship is expected to be on the agenda in the Turkey-US talks.
"Unlike other countries we are not announcing any arms deliveries to Kurdish formations", said Putin, who was speaking in Beijing.