"He enlisted in 2016 but has since not been sent out for basic training and his citizenship process has not moved forward."--Something is fishy here.  You typically don't sign the final contract blocks until the day you ship out for basic, in case something comes up before you leave that disqualifies you, or you get cold feet and decide to back out. All the tests you took the first day at MEPS have to be processed and verified, and a slot has to open up so a ship-out date can be established.  You're put on delayed enlistment until then, and the contract is signed and final oath of enlistment is taken the day you leave.  Perhaps his situation was different, but I don't recall anyone I went through MEPS with actually signing the full contract before the day they left for basic.