TOKYO (Sputnik) — On Wednesday, Pyongyang announced it had carried out a successful test of its first hydrogen bomb. Several states have subsequently called for new sanctions against the country. Later in the day, the UN Security Council condemned the alleged test, adding it would begin work on further anti-Pyongyang measures in a new resolution.
The two leaders agreed on close cooperation on the matter, with Japan ready to seek new UN sanctions against North Korea. The phone conversation became possible after the late 2015 settlement between the two countries of the World War II "comfort women" dispute, the agency said.
North Korea declared itself a nuclear power in 2005 and conducted nuclear tests in 2006, 2009 and 2013, having earlier withdrawn from the Nuclear Non-Proliferation Treaty that it ratified in 1985. Doubts have been expressed by the South Korean intelligence that Wednesday's blast was genuinely hydrogen-based.