Prime Minister Shinzo Abe and Mongolian President Khaltmaa Battulga agreed Wednesday to cooperate in dealing with North Korea's rising nuclear and missiles threat as well as economic matters.

The meeting, held on the sidelines of an economic forum in the Russian port city of Vladivostok, is the leaders' first since Battulga was elected president in July. Mongolia has diplomatic ties with North Korea, while Japan does not.

Abe told Battulga that North Korea's nuclear test Sunday, which followed the launch last week of a ballistic missile that flew over northern Japan, poses an "unprecedentedly grave and imminent threat" and is "totally unacceptable," according to the Foreign Ministry.