ISTANBUL — First, the United States and Turkey temporarily stopped issuing visas to each other’s citizens. Then the Turkish lira plunged on international markets, and most travel between the two countries was curtailed.
By midday Monday, fears rose that a minor diplomatic dispute threatened to flare up into a full diplomatic standoff.
But by evening, both sides seemed to be taking steps to ease tensions.
“This decision is very sad before anything else,” President Recep Tayyip Erdogan of Turkey told journalists at a news briefing during a visit to Kiev, Ukraine, sounding a rare conciliatory note. “It is regrettable that the U.S. ambassador in Ankara took such a decision.”
In a statement a few hours later, the U.S. ambassador, John R. Bass, said: “This was not a decision we took lightly. It’s a decision we took with great sadness.”
In Turkey, the Foreign Ministry called for an end to the visa suspension because it was causing “unnecessary victimization,” the Turkish state news agency, Anadolu, reported.
The confrontation is taking place against a backdrop of deteriorating relations between Turkey and the United States, NATO allies who are at odds over a number of issues: American support for Kurdish fighters in Syria; calls by Turkey for the extradition of a cleric in the United States who it says was behind a failed coup last year; and Turkey’s tilt toward Russia in the war in Syria.
The visa suspension came on Sunday evening, after a Turkish employee of the U.S. Consulate in Istanbul was arrested amid reports that another consulate employee was being sought by Turkish authorities.
The Turks accused the employee, Metin Topuz, of having links to the wanted cleric, Fethullah Gulen, who is living in self-imposed exile in Pennsylvania.
The U.S. Embassy said Sunday that it would suspend the processing of all nonimmigrant visas while it reassessed Turkey’s commitment to the security of its staff. Students, business travelers, tourists and diplomats all travel on such visas.
Within hours, the Turkish Foreign Ministry announced similar measures in the United States, adding that the suspension included electronic visas and visas bought at the border — the way most tourists and other short-term visitors enter the country.
The U.S. ambassador, in his statement, said the embassy had not been able to learn of the reasons for Topuz’s arrest or of the evidence held against him.
“The arrest has raised questions about whether the goal of some officials is to disrupt the long-standing cooperation between Turkey and the United States,” the ambassador’s statement said.
The measures, which threaten to create chaos for Americans flying into Turkey, do not appear to have been enforced at the border so far.
Investors were spooked nevertheless. The lira dropped more than 4 percent against the dollar on Asian markets, news agencies reported.
“It is a pretty serious historic crisis,” said Soner Cagaptay, a research fellow at the Washington Institute and the author of a book on Erdogan, The Last Sultan.
“Washington gave Erdogan the benefit of the doubt for the last 15 years of his many diplomatic transgressions, but this is different,” Cagaptay said.
The United States was so upset about the arrests of its local staff members because they are vital to providing the technical and contextual support in diplomatic missions, he said.
Topuz was formally arrested on charges of espionage, trying to overthrow the government and acting against the constitution. His address was printed in a pro-government newspaper, Sabah.
Another employee, at the consulate in Adana, Turkey, was arrested in March over similar accusations, but his case has not yet come to trial. Both men appear to have been charged in part because of ties developed with former security officials in the course of their work — raising questions about the safety of all local employees of U.S. diplomatic missions in Turkey.
Turkey’s decision to welcome the leaders of Iran and Venezuela in recent weeks has also upset the United States, Cagaptay said, as has Erdogan’s abandonment of democratic standards as he imposed a state of emergency after last year’s failed coup and then sought greater powers for the presidency in a referendum in the spring.
Turkey has detained dozens of foreign citizens on terrorism charges, including several Americans. It has become increasingly clear that they are seen as potential bargaining chips in Turkey’s efforts to force the extradition of Gulen.
Erdogan has also expressed anger over the charges brought against 15 of his bodyguards over their use of violence against protesters in Washington in May, and over court cases against a former Turkish Cabinet minister and three others in a case of conspiracy to violate sanctions against Iran.
President Donald Trump has praised Erdogan as a stalwart ally in the fight against terrorism. He said last month after a meeting on the sidelines of the United Nations General Assembly that ties between the two countries were “as close as we’ve ever been.”
On Monday, Justice Minister Abdulhamit Gul said in an interview on live television that no decision had been made to arrest any other U.S. employees, dismissing local news reports that prosecutors were preparing to detain another consulate worker.
The Istanbul Chief Prosecutor’s Office was quoted Monday as saying that a worker at the consulate in Istanbul, who was identified only by the initials N.M.C., had been invited to the prosecutor’s office for an interview. The man’s wife and child were taken into custody in the town of Amasya.
Two more people were detained in connection with the case of Topuz, the news channel NTV reported.
A U.S. official said that current visas remained valid, and that Turkish citizens could apply for visas in other countries while services in Turkey were suspended.