Kellogg, 80, was chief of staff of the National Security Council during Trump’s first term. In a social media post, Trump said Kellogg was with him “right from the beginning”, and that together, they “will secure peace through strength, and make America and the world safe again.”

During his election campaign, Trump promised to swiftly end the conflict in Ukraine through his relationships with Ukrainian President Volodymyr Zelensky and Russian President Vladimir Putin.