brussels nato urge countries step efforts enforce sanction north korea stop weapons test appeal diplomats say aim reclusive state trade partner suspect hold back penalties 29 ambassadors u.s.-led military alliance issue statement world power seek common response north korea sixth large nuclear bomb test amid fear way imperative nations implement thoroughly transparently exist un sanction make efforts apply decisive pressure convince dprk regime abandon current threaten destabilize path statement read refer north korea official name democratic people republic korea diplomats speak condition anonymity say concern exist sanction north korea fully enforce pyongyang remain trade partner namely china several african nations china african asian countries continue trade north korea governments say guinea-bissau malaysia china need tighten sanction enforcement say nato diplomat involve discussions resolve north korea crisis efforts impose fresh sanction pyongyang unite nations run opposition president vladimir putin resist restrictions oil export country say crisis resolve sanction nato directly involve nuclear crisis repeatedly call north korea abandon nuclear ballistic missile program nato secretary-general jens stoltenberg say separately plan travel south korea japan october nato urge trade partner step pressure north korea