South Korea must stay in line with U.S. and Japanese plans to keep North Korea "under siege," the chairman of the Lower House committee on foreign affairs said, referring to the policy of maintaining maximum pressure on Kim Jong Un's regime.

Just days after Kim's smiling sister invited South Korean President Moon Jae-in to a summit with her brother in Pyongyang — an overture he's yet to formally accept, Yasuhide Nakayama attacked Seoul's financial support of the regime.

"At this point, every grain of rice is a military resource," the member of Prime Minister Shinzo Abe's ruling Liberal Democratic Party who previously served as vice foreign minister, said in an interview Tuesday. He echoed his government's line that Kim Yo Jong's visit south was "smile diplomacy."