Bolton, a hard-line politician whom Trump fired by a tweet in September, told the Spanish daily La Razon that the possibility of an "October surprise" was very real.
"Would he have a fourth summit meeting with [North Korean leader] Kim Jong Un to declare peace on the Korean Peninsula and an end to their nuclear weapons program? Not that it would happen, but he would declare it. Might he decide to withdraw all US forces from Afghanistan even before the election? Could he say he was going to withdraw from NATO?" he suggested.
Bolton said he was not going to vote for either Trump or his Democratic rival, Joe Biden. He claimed Trump did not understand the subject matter of many deals he was signing but relied on his "gut feeling" to make political choices.
Trump expressed interest in withdrawing from NATO during his 2016 presidential campaign but after his inauguration, he said that the US would protect its allies in case Article V is invoked. In 2018, Trump reportedly mentioned several times in private talks that he wanted the US to quit the alliance.
John Bolton served as the 27th US National Security Advisor from 2018 to 2019. On 10 September 2019, Trump tweeted that he had informed Bolton that his "services are no longer needed", citing many disagreements between them.