At Jacques Little's private tank musem, our guide told us the tank has to be demilitarized. Part of the breechface must be machined away so as to render the gun unsafe to fire. The armor must be compromised so a huge chunk of a turret is cut out. It may be rewelded on, but its integrity would not be there if left alone. I was told when the T-72 was imported, it was only about $5k for the tank but $15k for the freight.
