North Korean leader Kim Jong Un has vowed to implement the 'toughest' anti-US policy before Donald Trump takes office as president. Experts say a quick resumption of Kim-Trump summitry is unlikely as Trump will first focus on conflicts in Ukraine and the Middle East. North Korea's support for Russia's war against Ukraine also poses a challenge to efforts to revive diplomacy. Kim called the US 'the most reactionary state that regards anti-communism as its invariable state policy' and said the US-South Korea-Japan security partnership is expanding into 'a nuclear military bloc for aggression'.