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.

Republican president Donald Trump has been highly critical of the Obama administration's apparent failures to screen individuals coming from largely Muslim countries in the Middle East, and Republicans may see the report as more evidence to support their hardline immigration stance.

An unnamed U.S. defense official said though other foreign troops sometimes disappear, the regularity of the Afghan troops going missing is "out of the ordinary" and should be a cause of concern. However, they added there is no evidence any of the individuals have committed crimes or present a threat to U.S. security.

Eight Afghan soldiers have been designated as absent without leave (AWOL) from their assigned military bases in September alone, Pentagon spokesperson Adam Stump told Reuters. He disclosed that the total missing since January, 2015 is 44.

"The Defense Department is assessing ways to strengthen eligibility criteria for training in ways that will reduce the likelihood of an individual Afghan willingly absconding from training in the U.S. and going AWOL (absent without leave)," Stump said, reassuring soldiers are always vetted before entry into the U.S. that they have neither committed any human rights violations nor are affiliated with radical militant organizations.