A clause that prevented Japan from having or using an army was entered into the new Japanese constitution after the World War II.
Step-by-step explanation:
The setback that Japan received after it was bombed by the United States made it surrender and agree to most conditions put by the allied nations under the leadership of the United States thereafter.
To cease the possibility of Japan rising for revenge and to make sure that regional peace isn't disturbed over and over again by Japan, General Macarthur insisted on the inclusion of this clause in the new Japanese Constitution which would restrict it from having an army of its own that it could use to establish its dominance in the region all over again.