ISTANBUL >> Americans planning an impromptu visit to Istanbul have been turned back. Board members of one school have had to postpone meetings. A Turkish entrepreneur, after spending two years setting up a business in New York, finds herself in limbo, her visa appointment canceled.

The cases, though apparently relatively few, signal the potential for deeper disruptions since the United States and Turkey suspended visa services two weeks ago in a tit-for-tat dispute over Turkey’s detention of U.S. consular employees.

This week, Deputy Assistant Secretary of State Jonathan R. Cohen devoted a whole day to trying to resolve the dispute during a visit to Turkey, and President Recep Tayyip Erdogan of Turkey expressed a desire to end the disagreement. But it appears far from over.

Alarmed at the arrest of two of its locally employed consular staff and the detention of the wife and daughter of a third employee, U.S. officials are demanding assurances that its staff members will not be arrested for carrying out U.S. business.

They are also demanding that those already arrested be released unless Turkey can provide compelling evidence against them.

Until then, things remain frozen.

Both countries have allowed travelers visas on humanitarian grounds, and people holding existing visas can travel, but a few Americans have been refused entry at Istanbul airport, and more have had to cancel their trips.

“It is having some impact on people’s plans for the mid- to long-term,” said Matthew Bryza, a former U.S. ambassador and chief executive of Lamor Corp. in Turkey.

He criticized the visa ban as the wrong tool, but said he was buoyed by the restraint in the language used by both sides to seek a resolution.

Thousands of Turks have had to suspend their plans, too. The visa shops and cafes lining the street opposite the U.S. Consulate in Istanbul were closed this week. A lone man typing in his office said there were no appointments at the consulate, so no business.

Up to 10,000 Turks a month are granted nonimmigrant visas to visit the United States, according to State Department figures, and 113,064 were granted in all of 2016. Nearly half a million Americans traveled to Turkey in 2016.

A fashion promoter was set to have her interview this week for an entrepreneur’s visa but was informed by email that her interview had been canceled. She asked that her name not be published but said she was dismayed that after two years of work and $100,000 of investment in an office in Manhattan’s trendy SoHo district, she faced new legal requirements and more paperwork reapplying in a third country.

Relations between Turkey and the United States have been strained since last year’s failed coup, which Turkey blames on Fethullah Gulen, a Muslim cleric who lives in self-imposed exile on a large estate in Pennsylvania.

Turkey has been upset by the United States’ perceived reluctance to extradite Gulen — the United States says Turkey has not provided evidence that would convince a federal judge — and by the United States’ arming of Kurdish forces in Syria, which Turkey fears will strengthen Kurdish separatists in Turkey.

The United States has been alarmed at the backsliding of democracy in Turkey in recent years under Erdogan and the mass arrests conducted since the failed coup that have even swept up a dozen Americans, some of whom have been in jail for over a year, and two long-standing Turkish employees of U.S. Consulates.

Hamza Ulucay, an employee with more than 30 years’ service at the U.S. Consulate in Adana, in southeastern Turkey, was arrested in March, accused of having ties to a terrorist organization. He is in jail awaiting a formal indictment.

Two weeks ago, Metin Topuz, who has worked at the Istanbul consulate for the Drug Enforcement Administration for over 20 years, was arrested on similar charges.

Days after his arrest, the Istanbul police searched the home of a third employee, Mete Canturk, who has also worked for years at the Istanbul consulate. He was not at home at the time, and officers then visited his wife’s family home in northern Turkey and detained his wife and daughter, who were attending the funeral of his wife’s father.

The recent detentions prompted the U.S. visa suspension, an unexpected and drastic action that seems to have halted the arrest of a third employee. Since the suspension, the Turkish police have not pursued Canturk, who has continued to work every day at the consulate.

But his wife and daughter were detained for more than a week in Asmaya. They were released Monday on the eve of the arrival of Cohen, the State Department official, but remain under judicial control and cannot leave the country.

The American action followed a similar turn in German-Turkish relations several months ago, when Germany reacted to the arrests of several Germans in Turkey by threatening economic sanctions and restricting support for Turkey’s application for membership in the European Union.

Turkish officials have indicated that they want the visa suspension to end.

“I don’t think that this is a problem that will drag on,” Erdogan said Thursday. “This delegation is here to finish it. The talks are ongoing. My wish is for a result as soon as possible, leave the visa issue behind and that relations return to its normal situation.”

Yet, in other comments later the same day to a gathering of party supporters, Erdogan continued to rail against U.S. policy, in particular at perceived American reluctance to extradite Gulen.

“They think we are strategic partners and that we will obey everything,” he said of U.S. officials. “Now they are asking me to give them some people. But first you should give me the one in the ranch,” a reference to Gulen and his Pennsylvania home.

Going into talks Wednesday, Cohen told Turkish journalists that the United States was seeking assurances that Turkey would not detain consular employees for contacts made in the normal course of their work, and that it wanted the arrested employees to be released or to be shown compelling evidence of their wrongdoing.

Turkish officials have concentrated on lifting the visa ban, suggesting that it would be resolved soon but offering no promises on the detainees.

“We will cooperate if their demands meet the rules of our constitution,” Turkey’s foreign minister, Mevlut Cavusoglu, said at a news briefing Wednesday. “But we will not succumb to impositions, and we will reject any conditions that we cannot meet.”

A senior presidential adviser, Ibrahim Kalin, later said that the visa ban would be resolved soon, but that details discussed would have to be referred back to Washington first.

By the fourth day of Cohen’s visit to Turkey, there was no announcement of an agreement.