Some immigrant U.S. Army recruits who were promised a path to citizenship have been abruptly discharged. The Associated Press first reported that recruits were being discharged, and now some are sharing their stories with CBS News.

Panshu Zhao, a Chinese-born American-educated Ph.D. student came to the U.S. in 2009 and is now teaching geology at Texas A&M University. When asked what fascinated him about America, he said "freedom."

He enlisted in the U.S. Army Reserve in 2016 through a program called Military Accessions Vital to the National Interest (MAVNI). It started under President Bush to help fight the war on terror, and offered non-citizens a fast track to citizenship if they had critical language and medical skills needed by the military.

Zhao speaks Mandarin, so he enlisted in 2016, right before the program was suspended under President Obama. That happened right as tougher screenings were mandated for recruits.

"They ordered so many background checks that they destroyed the program," said Margaret Stock, an immigration attorney.

Stock is a former Army lieutenant colonel who helped create MAVNI. She says not enough resources were provided for the additional investigations, resulting in a 10-year backlog. She's now representing Zhao, who was discharged in March.

"I didn't get my clearance and I asked them why and they refused to tell me why," Zhao said.

A Pentagon spokeswoman told CBS News MAVNI was suspended in 2016 because it was vulnerable to an unacceptable level of risk from insider threats such as espionage, terrorism and other criminal activity.

"I have never violated any legal rules. I have never been associated with any foreign forces and how could I fail this? Probably because the only thing I have is I'm Chinese. I was born in China. My parents are Chinese people. How could I change that?" Zhao said.

He passed a background check to teach at Texas A&M, and another to visit the White House.

"I wish I can at least have some certain degree of justice for this," he said.

Zhao is still teaching and would like to continue. But he's unsure about the future, because if he is deported, that could mean the Chinese government would see him as a traitor for pledging loyalty to the U.S. military.

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