http://sys1.tpusa.com/dir01/imprtgui
It has the following under Special Requirements Chapter 29
9. Arms, Ammunition, Explosives, and Implements of War. These items are
prohibited importation except when a license is issued by the Bureau of
Alcohol, Tobacco and Firearms of the Department of the Treasury,
Washington, D.C. 20226, (202) 927-7920, or the importation is in
compliance with the regulations of that department. The temporary
importation, in-transit movement, and exportation of arms and ammunition
is prohibited unless a license is issued by the Office of Defense Trade
Control, Department of State, Washington, D.C. 20520.
Not to be negative but they might consider a tank an "Implement of War"
you also might call Owen Export Service they have a site on the Internet.
They advertise military vehicles for sale.