President Donald Trump may withdraw the United States from NATO if he wins a second term, former national security adviser John Bolton said on Thursday. Bolton left the Trump administration in September 2019 after disputes over foreign policy. 

"It wasn't that we convinced him that NATO is actually a pretty good alliance, but that he just saw he couldn't go across the line and actually call for withdrawal ... once he's reelected, that political guardrail, if it doesn't disappear entirely, is substantially diminished,” Bolton told Times Radio.

Bolton said if the president wins a second term, Trump “doesn't have to worry as much about the U.S. political blowback, and so his instincts or his inclinations have free rein." The president has often shown disdain for multilateral organizations and agreements, viewing them as running counter to his “America First” agenda. 

In July 2018, Trump threatened to pull out of NATO during a summit in Brussels. He has frequently accused NATO allies of not contributing their fair share to defense spending. 

At other times, the president has defended the security alliance. 

In December, Trump attacked French President Emmanuel Macron for calling NATO “brain dead,” slamming his remarks as “very insulting.” Trump said NATO “serves a great purpose” and chided the French president as being “very disrespectful” to other alliance members. 

NATO was formed in 1949 and currently has 30 members. In the post-Soviet era, the pact conducted its first military interventions in Bosnia and Yugoslavia in the 1990s. In the years following the Sept. 11, 2001, attacks, the alliance began activites in Afghanistan and Iraq. NATO also enforced a no-fly zone in Libya in 2011. 

If Trump does withdraw the U.S. from NATO, it could have massive geopolitical implications, particularly in Europe where it could embolden Russia’s military activities in the East.