Bolton declares Trump not 'fit for office' in new interview after refusing to testify in impeachment saga

John Bolton has now called President Donald Trump not “fit for office” as he promotes his new book detailing claims of incompetence and wrongdoing.

The former national security adviser threatened to sue if subpoenaed by the House impeachment inquiry, but he told ABC News months later the president was unfit for office.

"There really isn't any guiding principle that I was able to discern other than what's good for Donald Trump's reelection," Bolton told ABC News in an interview that will air in full Sunday.

Bolton served 17 months in the White House, where he found the president "stunningly uninformed" and easily manipulated by foreign adversaries -- which he repeatedly asked for assistance in his re-election campaign.

The House impeached the president over his efforts to leverage military aid to Ukraine in return for election assistance, but the Republican-led Senate acquitted Trump after Bolton refused to testify about those efforts and, according to his book, similar requests to other foreign leaders.

Bolton accompanied the president on his two summits with North Korea's Kim Jong Un, his infamous Helsinki meeting with Russia's Vladimir Putin, and several meetings with China's Xi Jinping, Turkey's Recep Tayyip Erdogan and other world leaders.

"There was considerable emphasis on the photo opportunity [with Kim Jon Un] and the press reaction to it," Bolton told ABC News, "and little or no focus on what such meetings did for the bargaining position of the United States."