The two security units are counted double, so their manpower is 13,212 in equivalence. Add that to the fortified zone and you have 14,950 men in the city and the hex shows as blue which means its garrison is 100%.
But if I move out just the security regiment, the hex turns yellow which means it has dropped below the 100% requirement. But with a doubled security division of 9,854 in equivalence added to the Fortified zone to make it 11,592 in equivalent manpower left behind, I’m almost positive that Minsk is seen by the AI as heavy urban even though the mouse-over in my screenshot shows it as light urban. I guess it is also possible that the security troops are not being doubled in Minsk, but that would mean just this hex since Riga is garrisoned with two regiments and a fort without problems.
I have Riga garrisoned with two security regiments and a fortified zone which gives it about 8,500 in equivalent garrison value and it is blue, so this problem appears to be specific to Minsk right now. Though I haven’t gone very far east yet so other light urban centers may need to be looked at.
Jim

