Nice troll, but one Marine in a large force committing a horrible crime and then being punished isn't really indicative of a national policy. If it were, the US would also be supporting killing US soldiers on military bases in Texas due to MAJ Hasan's spree shooting a couple years ago.
OTOH, it's crazy that that guy got only 4 years. 10-20 would be more appropriate. Hopefully being convicted under Japanese law doesn't prevent additional action under UCMJ to run consecutively.