Pentagon officials believe 44 Afghan troops visiting the U.S. for military training have disappeared in less than two years because they wanted to live and work illegally in America, Reuters reported Thursday.

Though this is a tiny portion of the roughly 2,200 Afghan troops who have come for such training since 2007, it does raise embarrassing questions about security after the Obama administration has spent billions of taxpayer dollars on the program, which was meant to help the U.S. gradually leave the costly 15-year Afghanistan conflict.