Many Mavni recruits have been airing their concerns on Facebook. In interviews, some said they feared they could be deported.
H.J. Zhu, a Chinese national who signed an enlistment contract in January 2016, said that he has been calling his recruiter constantly because his student visa expires in two months and he has yet to receive a date to report for basic training.
“Emotionally, I can’t move forward with my life,” said Mr. Zhu, 27, who has master’s degrees in engineering from Columbia University and the University of Wyoming. “I am sure my contract is on the verge of being rescinded,” he added, because enlistees must report to training within two years of signing a contract.
Paul Haverstick, a Pentagon spokesman, confirmed that the Army must discharge recruits who have not shipped to initial military training within two years.
“Unfortunately, some Mavni recruits have been unable to complete the increased security screening required by the Department of Defense to ship to training within two years of enlistment,” he said, adding that the Army is still seeking ways to help those who have been affected.
“The Mavnis have become a huge problem for the recruiting command because they can’t ship out to their training until they complete mandated background checks,” said Margaret Stock, a retired lieutenant colonel in the Army Reserve who helped create the program. “If they can’t ship out, they aren’t doing the Army any good.”
Ankit Gajurel, a Nepalese mechanical engineer who enlisted in the Army Reserve in May 2016, recently had his training date postponed for the second time. But several of his references had been contacted by security officials, and he had been told by his recruiter that his “counterintelligence interview,” one of the last steps in the vetting process, would be scheduled for November.
“I was hopeful and happy things were moving,” said Mr. Gajurel, 24, who lives in Minneapolis.
Instead, last week his recruiter phoned him to say that he was a “Mavni loss” and instructed him to turn in his military identification and stop attending training drills with his unit in Colorado. “I felt blindsided when that came over the phone,” Mr. Gajurel said.
Ms. Stock said that with the end of the fiscal year approaching, the military offered “loss forgiveness” to recruiters of Mavni soldiers, a bureaucratic incentive to cancel their contracts so that they do not count against their performance.
Since 2009, more than 10,000 immigrants, mostly individuals on student or employment-based visas, have enlisted mainly in the Army. Mr. Anwar and Mr. Gajurel both came to the United States on student visas and then secured temporary work visas.
“I thought this would give me the opportunity to better myself and build my life in the United States as a citizen,” Mr. Gajurel said.
Typically, participants in the program are sworn in as citizens after completing basic training, without having to first obtain a green card or permanent residency, making the program the quickest path to citizenship available. In exchange, they serve eight years in the military. They can lose their citizenship if they fail to serve honorably.
The program’s success stories include Paul Chelimo, a native of Kenya who won a silver medal for the United States in the 2016 Olympics in Rio de Janeiro; Saral Shrestha, a Nepalese national, who was named the United States Army soldier of the year; and Dr. Marco Ladino, originally from Colombia, who works at the V.A. hospital in Miami.
Many have served as interpreters on military missions to Africa, Asia and the Middle East, or helped fill shortages of health professionals, like dentists. They also have trained American soldiers in language and culture.
Supporters of the program have advocated its expansion, saying it attracts a high caliber of recruits at a time when it is especially difficult to bring in well-educated, high-skilled Americans.
But critics have expressed concerns that terrorists could infiltrate it. There has never been a Mavni recruit charged with terrorism. However, dozens of native-born recruits have been charged with terrorism.
The program, which is renewed annually, has been suspended in the past.
Shortly after the November 2009 killing of 13 people at Fort Hood in Texas by an Army psychiatrist, an American-born son of immigrants, the program was suspended for about two years pending additional security reviews.
Immigrants with legal residency have long been eligible to join the military, but a law passed in the wake of the Sept. 11, 2001, attacks allows other documented immigrants to join if it is in the nation’s vital interest. Mavni applicants must have lived legally in the country for at least two years to be eligible.
Immigrants currently represent about 13.5 percent of the United States population. They constituted 18 percent of the Army soldiers in World War I and 43 percent of the Union Army during the Civil War. Immigrants represented 5 percent of those in the armed forces and about 8 percent of Army recruits last year.
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