When Japan renounced the military as an instrument of foreign policy, they weren't thinking about aliens.
Well Defense Minister Shigeru Ishiba, for one, finally is. He recently hinted that he's studying whether the country's pacifist Constitution would let them use military force against invading extraterrestrials. "There are no grounds to deny that there are unidentified flying objects and some life-forms that control them" he said.
To decide for yourself whether Mr. Ishiba is delusional or prescient play around with the Drake equation for calculating the likelihood of alien life existing in the Milky Way.