Article 9:
Aspiring sincerely to an international peace based on justice and order, the Japanese people forever renounce war as a sovereign right of the nation and the threat or use of force as means of settling international disputes. 2) In order to accomplish the aim of the preceding paragraph, land, sea, and air forces, as well as other war potential, will never be maintained. The right of belligerency of the state will not be recognized.
It was reinterpreted later to allow enough forces to defend Japanese territory, but not weapons that can be used only on others. There has been a debate for several years now to change this, but it has not happened yet. There is even an argument going on about whether nuclear weapons are allowed, but the original constitution basically disbanded the entire military.
But a lawyer will argue that atomic and nuclear was not stated so allowed. They can also say it is for defense against Rodan who is currently in China.