This US program inspired a comparable preference in Canada for citizenship applicants who had enrolled in the military in C-24:

Mohammed Anwar enlisted in April 2016 in the United States military through a program that promised him a fast track to citizenship. His ship date for basic training, expected within six months, was postponed twice. “It was common knowledge that there were delays because of new security checks,” said the 27-year-old Pakistani national, who lives in Jersey City.

Each month he donned a uniform and, as required, attended drill training with his Army Reserve unit in Connecticut.

Last week, Mr. Anwar got a call from his recruiter informing him that his enlistment had been terminated. “I was shocked, confused and angry that the United States government didn’t keep up with its commitment to me,” said Mr. Anwar, who was to work as a nurse.

The reason behind the decision to cut Mr. Anwar from the military remains unclear to him.

In the last week, recruiters have rescinded contracts for an unknown number of foreign nationals who had signed up for Military Accessions Vital to the National Interest, or Mavni, a program introduced in 2009 to attract immigrants with certain language and other skills that are in short supply into the armed forces.

More than 4,000 Mavni recruits have been in limbo since late last year, when the Department of Defense began introducing additional vetting. The protracted process has indefinitely delayed basic training for many enlistees, making it more difficult for recruiters to meet their targets. Recruiting stations are flooded with calls from many concerned that their lawful presence in the country could lapse while they await clearance.

“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 “I am sure my contract is on the verge of being rescinded,” he added, because enlistees must report to training within two years of signing a contract.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.