The White House has confirmed U.S. President Donald Trump will hold a summit with President Moon Jae-in on the sidelines of this week's G20 Summit in Argentina.br U.S. National Security Advisor John Bolton told reporters on Tuesday that Trump will also hold one-on-ones with Russia's Vladimir Putin, China's Xi Jinping and Japan's Shinzo Abe.br The Moon-Trump meeting comes amid a sharp slowdown in North Korea-U.S. diplomacy with a planned second summit between President Trump and Kim Jong-un pushed back until early next year.