Trump criticisms of South Korea while on the campaign trail were, like those of Japan, about defense.
MSNBC reported in May that the GOP candidate railed against the country in May for the cost to the U.S. of having a defense force on its soil.
"They're paying us a tiny fraction of what it's costing. I'd love to continue to defend Japan, I'd love to continue to defend South Korea - we have 28,000 soldiers on the line between North and South Korea right now. It's costing us a fortune, which we don't have, we're a debtor nation," he told the "Morning Joe" show.
"I'd like them to pay up. They have a lot of money, both of those nations, we take in Japan's cars by the millions."