President Donald Trump and his South Korean counterpart Moon Jae-in have exchanged views on how to make the upcoming US-North Korea summit a success, the presidential Blue House said, according to Yonhap news. The conversation took place in a Sunday phone call, in which the two leaders "exchanged opinions on various actions taken by North Korea recently," Moon's senior press secretary, Yoon Young-chan, said in a statement. It comes amid North Korea's threat to call off the June 12 meeting between Trump and Kim Jong-un, with Pyongyang slamming ongoing military exercises between South Korea and the US as a provocation and rehearsal for invasion.