But the USA doesn't consider the YPG a terrorist group and believes it's crucial in the fight against ISIS in Syria. The conflict between North Atlantic Treaty Organisation countries (mostly between the U.S. and the European Union from the one hand and Turkey from the other) has been brewing for a long time. Last month, he called to congratulate Erdogan on winning a referendum, widely criticized by other USA allies, that vastly increased presidential power in Turkey.
The goal of those visits was "to pave the ground for fruitful discussions between the two presidents".
The United States and Turkey are seemingly not on the same page regarding confronting terrorism as the United States is colluding with Syrian Kurds after the U.S. has set a key objective of defeating ISIS militants; however, Turkey has taken a stand against arming Kurds, perceiving Kurds as terrorists.
Turkish dissidents in the United States say they do not expect a breakthrough for Erdogan's extradition demand during his visit with Trump.
The same goes for Zarrab, who was arrested in Miami in March past year and was linked to a 2013 corruption scandal that ensnared the government when Erdogan was prime minister.
Yıldırım might have stated "we are not in a position to declare war on the USA", but it also means that we would be on the verge of conflagration if it were possible to challenge the world power. Bozdağ presented new evidence supporting the accusation that Gülen was involved in the attempted takeover as the process between Turkish and USA judicial authorities continues in terms of procedure.
He said the United States had assured Turkey the region's demographics would not change as a result of this, a key concern for Ankara. As evidence, it points to US weapons seized from the PKK - saying they were funneled from the YPG - and the fact that the United States has been unable to dislodge Kurdish fighters from controlling Arab parts of northern Syria that they have seized, with USA assistance under Obama, along the Turkish border.
It's not clear, however, whether Erdogan expects to be able to dissuade Trump during their meeting, and what action he is prepared to take if the USA goes ahead with the policy.More news: Trump Denies Asking Ex-FBI Director Comey to Drop Flynn Inquiry
More news: HUDCO shares surge 29 percent on trading debut
More news: WhatsApp Users On Android Can Now Pin Important Chats
The president, on the other hand, rightly considers the YPG the most effective boots on the ground in Syria against Islamic State, and is preparing it for the coming battles to eradicate Islamic State control of Syrian territory.
"In the case of Gulen, the United States needs to be clear in terms of what it can and cannot do", said Aydintasbas and Kirisci. A recent bombardment of the PKK position in Sinjar, Iraq, served as a reminder of Turkey's frustration. The YPG is the main component of the SDF. "It's the same story. We keep on explaining that it's not the only alternative, and they keep saying it's the only alternative". We have fought in Somalia, in Kosovo, in Macedonia, in Bosnia-Herzegovina.
Some senior Turkish officials last week said the US policy toward the YPG amounted to support for terrorism, putting the government on an apparent collision course with Trump ahead of Erdogan's meeting.
"The arming of the Syrian Democratic Forces is going to be very important for the liberation of Raqqa".
The Britain-based Syrian Observatory for Human Rights said the Kurdish-led Syrian Democratic Forces, backed by U.S-led coalition airstrikes, advanced as they clashed with the militants in a multi-pronged offensive northeast and northwest of the city.
Even so, Turkey is a part of the USA -led coalition fighting Islamic State, and US jets conduct airstrikes against the group from Turkey's Incirlik Air Base.
The reported advance comes a day after SDF commanders said they would launch their assault on Raqqa, the last large IS stronghold in Syria, by early summer.
Turkey also retains the option of canceling an agreement that allows US and anti-Islamic State coalition warplanes to fly out of its air base at Incirlik.