The other countries that have borders along Russia and Belarus are tightening their borders because of concern about Russian agents being placed in areas where they could wreak sabotage or cause havoc. Based on reports that I read indicating that Ukraine is having a difficult time accommodating for POWS, I doubt that Ukraine has the ability to monitor huge numbers of men mingling in with the rest of society. If the Russians heard that asylum was being granted to defectors they would certainly take advantage of the situation.