Over the course of 12 months, the U.S. Army discharged more than 500 immigrant enlistees who were recruited across the globe for their language or medical skills and promised a fast track to citizenship in exchange for their service, The Associated Press has found.

The decade-old Military Accessions Vital to the National Interest recruiting program was put on hold in 2016 amid concerns that immigrant recruits were not being screened sufficiently. The Army began booting out those enlistees last year without explanation.

The AP has interviewed more than a dozen recruits from countries such as Br...