The conversation took place on the eve of US Secretary of Defense James Mattis’ first official visit to South Korea, during which he will meet Defense Minister Han Min-koo. The sides are likely to discuss North Korean missile and nuclear threat and deployment of US Terminal High Altitude Area Defense system (THAAD) missile defense system in South Korea.
On Sunday, US President Donald Trump and South Korea's acting President Hwang Kyo-ahn discussed security measures to tackle potential threat posed by North Korea, the White House said in a statement.
In July 2016, Seoul and Washington agreed to deploy a THAAD system in South Korea's Seongju County and in mid-December the White House confirmed that no change in the plans was expected despite the South Korean parliament's vote for President Park Geun-hye's impeachment.
On September 5, 2016, Pyongyang launched three ballistic missiles in the direction of the Sea of Japan. Several days later it conducted a successful test of a nuclear warhead, which is believed to be the fifth and largest blast since Pyongyang began pursuing nuclear and ballistic missile programs.
