Because they went in to protect their own interests in the world after the world war 2. They dropped 2 nukes on Japan, remained in the country, and now they want money. Crazy people.

We also wrote their constitution that they can't have a military.

They still have the jdf but we kinda forced this position, it's a bit of a baffling question.

Of course it's only baffling if you assume it's asked in good faith.