mexico city mexican government thursday say declare north korean ambassador mexico persona non grata protest country nuclear test unusually firm step move closely line washington statement government say give kim hyong gil 72 hours leave mexico order express absolute rejection north korea recent nuclear activity describe grave threat region world mexico traditionally seek steer clear diplomatic ructions past months adopt robust language condemn governments venezuela north korea descend increase international isolation face rocky relationship u.s. president donald trump due threats tear north american free trade agreement nafta mexico back diplomatically issue imply great political cost government north korea nuclear activity serious risk international peace security represent grow threat nations region include fundamental ally mexico like japan south korea mexican government say mexico step follow tide international condemnation north korea repeat missile launch recent weeks intensify follow nuclear test sunday official mexican foreign ministry note however president enrique pena nieto government break diplomatic tie north korea mexico expel north korean ambassador nuclear test