Before leaving his house each day, Castillo Javier Police always made sure he carried the essentials. Hat. Wallet. Birth certificate. But the last item still did not stop him from being detained — and then deported.

While picking up groceries one night this summer, he was stopped by Dominican immigration authorities. He pulled out the document showing that he was born in the Dominican Republic. Still, the officials bused him to a detention center.

Days later, Mr. Police, 21, was expelled to Haiti, a country he had never been to and is so mired in gang violence that the United Nations on Monday approved a Kenya-led security mission to the country to help quell the unrest.

“I don’t know anyone in Haiti,” Mr. Police said. “How am I going to go back to the Dominican Republic? How are my mother, father and brother feeling right now?”

Mr. Police is one of roughly 130,000 descendants of Haitian migrants living in the Dominican Republic without citizenship despite being born there, according to human rights groups. Many with birth certificates are considered essentially stateless, their status the result of a 10-year-old court order ruling that children of undocumented migrants are not entitled to citizenship.

The decision has left many of those children walled off from affordable health care, career opportunities, higher education or even high school diplomas.

Now, human rights groups and Dominicans themselves warn that they are being targeted for expulsion, in an intensified deportation strategy that the government says is aimed at those in the country illegally.

The crackdown comes as the Dominican government tries to cope with the surge of Haitians crossing the two countries’ shared border following the assassination of Haiti’s president, Jovenel Moïse, in 2021, which set off a wave of unrelenting gang violence in the country’s capital.

The number of deportations soared last year, sending more than 113,490 people to Haiti. That figure is already on pace to double this year, according to the Dominican government’s migration data.

But people born on Dominican soil are also increasingly a focus of deportations. In the past year, human rights groups say they helped at least 800 people return to the Dominican Republic after being expelled.

“They live in fear,” said María Bizenny Martínez, a coordinator for Socio-Cultural Movement of Haitian Workers, an advocacy group in the Dominican Republic. “Fear that they will be expelled. Fear that they will be left on the other side of the border without family because it has happened.”

The expulsion of the stateless Dominicans violates the Constitution, Ms. Martínez said, and the United Nations has warned that the removals also risk violating international law.

While only roughly 30 countries worldwide offer unrestricted birthright citizenship, nearly every nation in North and South America has adopted the policy.

In the Dominican Republic, however, a 2010 constitutional amendment and the 2013 court ruling not only excluded Dominican-born children of undocumented migrants from citizenship, but also instructed officials to audit birth records and relinquish the citizenship of those who no longer qualified, casting thousands into legal limbo.

Facing pressure from the international community, the government in 2014 introduced a program that would allow some of the stateless to regain their citizenship if they had been previously registered by their parents as being born in the Dominican Republic or if they separately started a new application process to naturalize.

But thousands were confronted with tight deadlines and bureaucratic delays. Many were unable to register and even those who did are still waiting for their identification documents.

President Luis Abinader, who is running for re-election next year, has said his immigration policies are necessary to ensure the Dominican Republic’s national security after Mr. Moïse’s killing set off widespread unrest.

Mr. Abinader is constructing barriers across the border with Haiti. Last month, he shut down the entire border over what his administration said was the unsanctioned construction of a canal on a river that flows between the two countries.

The expulsions are part of a broader campaign by the Dominican Republic against people of Haitian descent that human rights organizations and even the U.S. government have described as xenophobic and discriminatory.

The U.N. last month condemned the targeting and detention of pregnant Haitian women on their way to medical appointments in the Dominican Republic. Last year, the U.S. State Department warned that “darker skinned” Americans visiting the Dominican Republic could be profiled and detained, and cautioned about Dominican officials “arbitrarily” deporting its own citizens “primarily on the perception they could be undocumented Haitian migrants.”

The Inter-American Commission on Human Rights said last week that the lack of citizenship “has resulted in boys dropping out of school, entering the work environment at a very young age, while girls are at risk of being subjected to abusive relationships or human trafficking.”

In response, the Dominican minister of foreign affairs, Roberto Álvarez, released a statement saying the government was “committed to promoting policies and programs that foster inclusion, equality and nondiscrimination and respect for the ethnic and racial diversity of Dominican society.”

Mr. Álvarez declined a request to be interviewed. A government spokeswoman did not respond to a request for comment.

Mr. Abinader’s administration has rejected claims that his government violates human rights, saying that such accusations lack evidence and that the Biden administration has also been accused of xenophobic treatment of Haitian migrants.

The president has also said the pressure should be on the international community coming to Haiti’s aid rather than solely criticizing the nation at its doorstep.

“There is no Dominican solution to Haiti’s problem,” Mr. Abinader said last month. “We cannot be asked for more than what we already do.”

Yet Dominicans say that without citizenship, they must constantly live on guard, keeping documents with them and always being prepared to get stopped at security checkpoints, even in the streets of their hometown.

The concern among the stateless population is compounded by the occasionally cooperative, but often charged and even violent history between the two neighboring countries on the island of Hispaniola.

Haiti is the Dominican Republic’s third-largest trading partner, and more than 25 percent of Haiti’s official imports come from the Dominican Republic, according to the International Monetary Fund. The Dominican Republic also relies on Haitian laborers for its agriculture and construction industries.

For people like Liliana Nuel, an aspiring nurse living in Sabana Grande de Boyá, the policy means even walking to work can be a struggle. While four months pregnant, she said she was grabbed by an immigration officer while on her way to her hospital internship this year.

“They stopped me because of racism, because of my skin color,” Ms. Nuel, 29, said, adding that the officers clearly thought she was a migrant even though she was born in the Dominican Republic to Haitian parents. “We keep suffering so much discrimination because of that when I’m really in my own country.”

The authorities let Ms. Nuel go only when she showed them the nursing uniform packed in her bag.

Mr. Police was not so lucky.

After he was detained in late July, he was dropped off in Port-au-Prince, Haiti’s capital, 80 percent of which is thought to be controlled by gangs. With the help of advocates who heard about his case, he booked a hotel room and spent two weeks inside, only going out for food.

He was eventually put in contact with the U.N., which helped him secure passage back across the border after two weeks in Haiti. Before he left, he said a U.N. officer sent his photograph to Dominican immigration officials letting them know he was Dominican-born with a birth certificate and was one of 750 people that a former president said would be naturalized, though it had yet to happen.

Yet when he made it across the border, he was quickly detained and sent back to Haiti.

On a second attempt, the U.N. was again able to help him get back home.

After a decade without citizenship, he says the country he calls home should form a plan to provide stability for people like him.

“It doesn’t matter if the documents say we’re foreigners, we were raised in the D.R.,” Mr. Police said. “These people are born and raised in the D.R., same as me.”

Emiliano Rodríguez Mega contributed research from Mexico City.