President Recep Tayyip Erdogan is pushing a radical solution — resettling refugees in a swath of Syrian territory controlled by the United States and its Kurdish allies. If that does not happen, he is threatening to send a flood of Syrian migrants to Europe.

Mr. Erdogan has long demanded a buffer zone along Turkey’s border with Syria to keep out Kurdish forces, whom he considers a security threat.

But he has repackaged the idea for the zone as a refuge for Syrians fleeing the war — acting as resentment against Syrians in Turkey has increased, and a Syrian and Russian offensive in Syria has sent hundreds of thousands more refugees fleeing toward the Turkish border.

“Our goal is to settle at least one million Syrian brothers and sisters in our country in this safe zone,” Mr. Erdogan told leaders of his Justice and Development Party in Ankara last week. “If needed, with support from our friends, we can build new cities there and make it habitable for our Syrian siblings.”

None of the other powers involved in the war in Syria has wholly agreed to the idea, but Mr. Erdogan is demanding immediate access to the territory or threatening take it himself. If not, he said, he would “open the gates” for large numbers of refugees to head into Europe, as they did in 2015.

The European Union has given Turkey about $6.7 billion since 2015 to help control the flow of migrants. But Turkey, which has given sanctuary to 3.6 million Syrians, says the migrant problem is growing exponentially.

“If there is no safe zone we can’t overcome this,” Mr. Erdogan said on Saturday.

Syrians have already turned their sights on Europe again. Turkish and international refugee officials have reported an increase in migrants and refugees trying to cross by boat into Europe from Turkey, many of them Syrians leaving Istanbul since the police crackdown. Over 500 refugees arrived by boat in the Greek island of Lesbos in a single day late last month.

Mr. Erdogan was long seen as a champion for Syrian refugees. His tougher policy on them comes after his party suffered a humiliating defeat in the election for mayor of Istanbul in June, and as a deepening recession, soaring unemployment and inflation have stoked antiSyrian feeling among Turks.

Officials are cracking down on Syrians working illegally or without residence papers, fining employers and forcing factories and workshops to close. Pro-government media have grown more critical of Syrians, landlords are raising their rents, and social media is bursting with anti-Syrian comments.

Local officials, many from Mr. Erdogan’s party, deny that the government is deporting refugees but support the crackdown, saying Syrians must live within the law.

The change is evident in places like Esenyurt, a working-class district of Istanbul. A district spokesman, Fatih Yilmaz, said the municipality was providing buses for around 100 people a week to return to Syria. He said the departures had pleased Turkish citizens, even if factory owners complained they had lost workers and landlords had lost tenants.

For Syrians living in Turkey, the shift in policy and attitude is a painful shock.

“It’s a disaster for Syrian people,” said Mohanned Ghabash, an activist who works for a nongovernmental organization in the southern town of Gaziantep, near the Syrian border.

Syrian workers were being told to acquire work permits and pay social security, he said, but many say they cannot afford the extra costs, and even if they can, they fear more rules will be enforced, including one that demands five Turkish citizens have to be employed for every Syrian in a company.

Police officers in Gaziantep visited a street of Syrian grocery and pastry shops and told store owners to remove the Arabic lettering from their shop signs or face a fine, enforcing a local law that had been ignored for eight years. The Syrians complied, painting out the Arabic and hanging Turkish flags in solidarity, but some said they were angry since it would cost them business.

Mohammad al-Azouar, whose family operated a well-known pastry shop in Aleppo, Syria, dutifully covered up a verse by the poet Rumi on the wall inside his shop.

“One fine from the police would finish me,” he said. “I am no burden. I came with my own money, just don’t squeeze us by the neck; let us survive.”

Syrians, who now make up 20 percent of the population in Gaziantep, have transformed the city, investing capital, and bringing business skills and cheap labor.

Most of them come from Aleppo, Syria’s second largest city and formerly a sophisticated cultural trading center. They have built a neighborhood of textile factories in Gaziantep, where Turkish and Syrian companies share buildings and workers. Hundreds of cafes, restaurants and pastry shops there cater to Syrians.

In the old city, Syrian stone masons have restored some of the crumbling monuments, and skilled Syrian coppersmiths from Aleppo have found a place alongside Turkish artisans, beating intricate designs into copper jugs and platters in tiny workshops.

Ibrahim Nahlas, 55, a renowned master craftsman from Aleppo who sells his wares across the Middle East, said he had longstanding business ties with Turkish craftsmen. “You have to have respect, then you will not have any problem,” he said.

Nour Mousilly, a textile manufacturer who lost a $12 million factory in Aleppo in the war, brought trained workers with him as well as a customer base in the Middle East when he started anew in Gaziantep, making men’s underwear.

“We already had our international partners so you could throw us anywhere and we can work,” he said, which makes his business a net benefit to Turkey’s economy.

Syrian big business owners said if you followed the rules you could still work in Turkey even if the profit margins were down. But smaller businesses and laborers expressed concern at the changing atmosphere and crippling fines that have already forced factory closings.

“The factories laid us off because we have no work permits,” Ahmed Atalai, 24, said as he waited with a group to cross the border into Syria. He left Istanbul, but after a month looking for work in southern Turkey where he was registered, was leaving the country. ”There’s no work.”

Mayor Fatma Sahin, a senior official in Mr. Erdogan’s party, has been a strong supporter of Syrian refugees for the economic lift they have brought the city, but she said they have to obey Turkey’s laws.

“What we say to the Syrians is there are rules to live here, so you have to obey those rules,” she said.

But Syrians see the new policies are aimed at making them leave. “They need to make us think it is better to go back to the safe zone,” said Abdulkarim Alrahmon, who runs a branch of a well known Syrian perfume company in Gaziantep.

The vans and buses of Syrian refugees arrive almost hourly at the border crossing near the town of Kilis, adjoining a Turkish-controlled area of northwestern Syria. Syrians living nearby said the police were depositing unregistered refugees directly across the border.

The Syrians being deported represent only a fraction of the Syrian refugees in Turkey.

But the deportations send a sharp message to Mr. Erdogan’s political opponents that he is taking action to reduce the number of refugees, and are a signal to Europe and the United States that he needs a new solution.

In Gaziantep, Mayor Sahin said she supported the plan for a safe zone in Syria and expected that half of the 500,000 Syrian refugees in her province would move there.

“Half of them will go, if opportunities are met and schools start to operate, she said. “They have to feel safe.”

The United States and Turkey agreed in principle last month to establish a jointly patrolled zone for refugees along the border. But they are still negotiating the details, and major differences remain.

Mr. Erdogan wants the zone to be 20 miles deep and run for 300 miles along the Turkish-Syrian border east of the Euphrates. The United States has limited Turkey’s access to a few miles.

American and Turkish troops conducted their first joint patrol of a small zone on Sunday.

But Syria has already called the plan a violation of its sovereignty and Russia emphasized the need to preserve Syria’s territorial integrity. The Kurds oppose the deal but have reportedly pulled back heavy weaponry from part of the border area.

American officials are focused on preventing clashes between Turkish and Kurdish forces.

“Present conditions are not conducive to organized returns and repatriation of Syrian refugees in safety and dignity,” Lanna Walsh, spokeswoman for the International Organization of Migration, said.

But she added that the group, in line with the United Nations, recognized that “not all areas inside Syria are unstable” and “recognizes the right for people to return.”

Syrian refugees remain circumspect about the safe zone. Some oppose any Turkish military expansion into Syria, but many still see Turkey as their best ally and a Turkish-controlled safe zone preferable to Syrian government or Kurdish control.