McMaster, former national security adviser to former U.S. President Trump, said in his new book that although Russia interfered in the U.S. democratic election, Trump ignored the opposition of his staff and remained determined to maintain good relations with Russian President Putin during his term.

"After more than a year in this job, I still can't comprehend Putin's hold on Trump," McMaster told his wife in March 2018, according to an excerpt from his memoirs.

McMaster took office in February 2017. He revealed that from the beginning, it was difficult to discuss Putin and Russia with Trump because Trump linked all topics involving Russia to the FBI's investigation into Moscow's interference in the 2016 election and possible links to the Trump campaign, which lasted throughout Trump's presidency.

McMaster said that Trump was overconfident and in the early days of his administration, he tried to improve relations with Russia by establishing a personal relationship with Putin, but Putin took advantage of Trump's vanity and insecurity, flattering Trump with sweet words and playing Trump in the palm of his hand.