Continuing his campaign, Trump held a rally in Conway, South Carolina on Saturday. The state will hold a primary election on February 24. 

Trump said he told a NATO meeting during his presidency that the United States would not defend "negligent" countries as long as he was in charge. 

"The leader of a major country stood up and asked, 'Sir, if we don't pay and Russia attacks, will you protect us?" Trump said, adding that he responded, "You didn't pay, you're negligent." 

Trump said, "No, I wouldn't protect you. In fact, I would encourage them to do whatever they want to you. You have to pay. You have to pay the bills," he said. 

In 2014, after Russia annexed Crimea, NATO decided to end its post-Cold War spending cuts. NATO countries agreed to spend 2 percent of their GDP on defense by 2024.

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During the 2016 campaign, Trump said that the United States would not fulfill NATO obligations for allies that did not meet the 2 percent quota. NATO said that by 2022, 7 out of 30 (31 by 2023) NATO members will meet this limit. This number was 4 in 2014. 

White House spokesman Andrew Bates reacted to Trump's remarks, saying, "Encouraging the occupation of our closest allies by a murderous regime is appalling and insane. It also jeopardizes U.S. national security, global stability and our economy."