Donald Trump in South Korea

BRENDAN SMIALOWSKI/AFP/Getty Images

President Donald Trump gestures to South Korean President Moon Jae-in during the 72nd United Nations General Assembly on September 21, 2017.

Japanese Prime Minister Shinzo Abe shares Trump’s hard-line stance on tackling Pyongyang, while South Korean President Moon Jae-in has a toned-down approach of engagement.

“Korea passing is a genuine concern,” said Robert Kelly, associate professor at Pusan National University, noting that Moon’s critics often use it against him. “It is clearly the case that Trump and his flamboyant style have taken over the North Korea debate in 2017 and pushed Seoul aside. I would be worried if I were the South Koreans.”

Some in South Korea even fear that a major provocation from their northern neighbor could result in Washington staging unilateral military operations. In response to Trump’s “fire and fury” threat against dictator Kim Jong Un, Moon warned in August that “no one should be allowed to decide on a military action on the Korean Peninsula without South Korean agreement.”

Further exacerbating the matter is the fact that the White House still hasn’t nominated an ambassador to South Korea, a position that’s been vacant since Trump took office in January.

To strengthen the bilateral alliance, there are four key principles the U.S. leader must follow when he meets Moon on Nov. 7, experts said.