'Human scum and bloodsucker' - Bolton's White House appointment fans worries over hawkish record in Asia

FILE PHOTO: Former U.S. Ambassador to the United Nations John Bolton speaks at the Conservative Political Action Conference (CPAC) in Oxon Hill, Maryland, U.S. February 24, 2017. REUTERS/Joshua Roberts/File Photo

SEOUL (Reuters) - Once rejected by North Korea as "human scum," U.S. President Donald Trump's latest pick for national security adviser has called for regime change in North Korea, prompting worries in Asia ahead of a historic summit between Washington and Pyongyang.

Trump announced in a tweet he was replacing H.R. McMaster with John Bolton, a former U.S. ambassador to the United Nations who has advocated the use of military force against North Korea and Iran and has previously been rejected as a negotiating partner by Pyongyang.