ANKARA, Oct. 10 (Xinhua) -- Mutual visa suspension is a crucial signal of the tense Turkey-U.S. relations which have turned from bad to worse, as the two NATO allies are facing the toughest challenge, local experts said Tuesday.
Visa suspension is the harshest measure taken by Ankara and Washington in their undulate relations because it will directly hurt their citizens, said Deniz Zeyrek, daily Hurriyet columnist.
The latest spat came after the arrest of Metin Topuz, a Turkish employee of the U.S. Consulate in Istanbul, over "espionage" and suspected links to Fethullah Gulen, a U.S.-based Muslim cleric accused by Ankara of masterminding a failed military coup in July 2016.
The U.S. Embassy to Turkey has slammed the arrest, saying allegations against the employee were "baseless" and Washington is "deeply disturbed by the arrest."
On Sunday, the U.S. Embassy announced the halt of all non-immigrant visa services in Turkey while it reassessed Turkey's commitment to the security of its missions and staff. Hours after the U.S. decision, Turkey retaliated by suspending all non-immigrant visa services at its diplomatic facilities in the United States.
Turkish Foreign Ministry summoned Charge d'Affaires of the U.S. Embassy in Ankara on Monday, urging the end of its "disproportionate" visa measure.
Also on Monday, the Istanbul Chief Public Prosecutor's Office summoned a staff member of the U.S. Consulate in the city to testify as a suspect.
On the same day, his wife and son were detained in the Black Sea province of Amasya on charges of supporting the Gulen Movement.
"I hope the U.S. will review its decision," Turkish Justice Minister Abdulhamit Gul said in a televised interview, adding that Turkey is "open to pursuing judicial cooperation" with the U.S. but stressing that the government would not intervene in judicial decisions.
In a statement late Monday, U.S. Ambassador to Turkey John Bass said the duration of the suspension of visa services in Turkey is unknown, as it depends on the discussion with Turkish government about the reasons of the U.S. Consulate staff member's detention.
The U.S. administration seems to understand that Turkey is conducting a "hostage policy," Zeyrek said.
He pointed to Andrew Brunson, a U.S. pastor who has lived in Turkey for more than 20 years, has also been jailed since last year for alleged links to Fethullah Gulen.
Hamza Ulucay, another local employee of the U.S. consulate in the southern province of Adana, was arrested on charges of being a member of the anti-government Kurdistan Workers' Party (PKK) on March 7.
U.S. officials earlier expressed "unease" over arrest of American citizens, but there was no indication for visa suspension, a Turkish official told Xinhua on condition of anonymity.
Washington was pressing Turkey to return a "cleric" while refusing to hand over another "cleric," Turkish President Recep Tayyip Erdogan has said, referring to Turkey's repeated calls for the extradition of Gulen.
Turkey-U.S. relations have been in a tense state because of the latter's support to Syrian Kurdish People's Protection Units, which Ankara sees as an offshoot of the PKK, the trial crisis against Erdogan's guards after a brawl during his visit to Washington in May, and the decision of Ankara to buy S-400 missile system from Russia.
Tension with Washington was exacerbated over an indictment last month by a U.S. court for Turkey's former Economy Minister Zafer Caglayan, who is charged with conspiring to violate U.S. sanctions on Iran.
"The U.S.-Turkey relations are falling into decline since 2013 with the Syrian crises. Visa restriction is a very crucial step in this crisis," said Bahadir Kaynak, an international relations associate from Altinbas University.
Citing the ongoing dispute between Turkey and Germany over arrested German citizens, Kaynak said Ankara would continue facing problems with other countries amid this "trend of arrest."