In his article, published by the German newspaper Der Tagesspiegel, Siebert recalled that later this week Biden will visit a totally different country from the Turkey he saw six months ago in terms of the Washington-Ankara partnership.
Washington is clearly concerned about the situation, Siebert wrote, pointing to the US government's scrapped plans to send US Secretary of State John Kerry to Turkey in early August.
Siebert also recalled that the representatives of the Turkish government and the country's state-run media insist that it was Washington which masterminded the attempted coup against President Recep Tayyip Erdogan.
Yes, if Gulen's extradition is rejected by US court, that will negatively affect US Turkey relations, but who will be the biggest loser— Sinan (@BeyazitsinanG) 11 августа 2016 г.
Turkey's leadership specifically pointed to the fact, Siebert wrote, that Turkish cleric Fethullah Gulen, who is accused of orchestrating the coup, now resides in the US, and that a former US State Department member was in attendance at an Istanbul conference when the coup took place.
In this vein, Siebert referred to the results of the latest opinion polls, in which two out of three Turkish respondents said that they believe Washington was involved in instigating the coup. Siebert also quoted Erdogan as saying that America must choose between Gulen and Turkey, a warning that was echoed by Turkish Prime Minister Binali Yildirim, who said that Washington's choice to give Gulen asylum in the US may "destroy" bilateral relations.
In this connection, Siebert recalled Erdogan's recent visit to Russia, where he met President Vladimir Putin and praised Moscow's "unambiguous" condemnation of the failed coup in Turkey.
Of course, this is not the only reason for the burgeoning dispute between Ankara and Washington, which have closely cooperated since the 1950s, Siebert wrote, referring to Ankara's dissatisfaction with American support for the Kurdish militias in Syria, where the US is fighting Daesh terrorists.
Earlier, CNN quoted the White House as saying that Biden is due to visit Turkey on August 24. He will meet Erdogan and Yildirim "to discuss the US-Turkey relationship and a range of issues of importance to both nations."
Also high on the agenda will be Ankara's request for the extradition of Gulen, who is currently living in exile in the Unites States.
Turkish Justice Minister Bekir Bozdag, for his part, said earlier this month that if the US government refuses to extradite Gulen, it would be effectively sacrificing its relations with Turkey for the sake of a terrorist.
On July 15, the Turkish authorities said that an attempted coup was taking place in the country; however, it was suppressed by the next day. About 250 people died during the coup attempt.