A new South Korea-US alliance must begin with increased understanding and mutual respect, a close ally of South Korean President Moon Jae-in said Tuesday, insisting the United States must understand why Seoul has no choice but to be patient and seek to peacefully denuclearize North Korea.

"One of the key things the 'returned America' should be different in is that an alliance must begin faithfully from values that both sides must respect as allies," Yang Jung-chul said in a paper posted on the website of the Washington-based Center for Strategic and International Studies (CSIS).

The visiting South Korean scholar was referring to US President Joe Biden's widely published declaration that "America is back."

Yang is said to be one of the closest confidants of Moon. They both served at the presidential office of Cheong Wa Dae under late President Roh Moo-hyun.

Yang also worked as the head of the Institute for Democracy, a think tank run by Moon's ruling Democratic Party, before he joined the CSIS earlier this year. He returned home this week.

"South Korea achieved success in much of the areas including security, market economy, and democratic system thanks to the support of the United States and the alliance between the two countries from the time of the post-war reconstruction period," wrote Yang, noting South Korea has become the world's 9th largest economy in less than 70 years since the end of the 1950-53 Korean War.

"This is like a beautiful journey of a strong South Korea-US alliance and a great victory for democracy."

The alliance, however, suffered a setback under Donald Trump, Yang argued, noting that South Koreans felt "offended" as they felt the previous US administration sought to convert values of the alliance into money in their defense cost-sharing negotiations.

Yang insisted the allies continue to face challenges as they "naturally" hold different views on a range of issues, including nuclear-armed North Korea.

"The United States must acknowledge that the fear and wariness of war is greater in South Korea and understand the reality that South Korea has no choice but to adopt methods of patience, dialogues, and peace along with persuasion and pressure," he said.

The intensifying rivalry between the United States and China poses another challenge for the alliance as Seoul increasingly feels pressured to choose sides, Yang noted.

"Asking South Korea whose side it is on is a very fragmentary and superficial question," he said.

"From South Korea's standpoint, the US needs to understand that South Korea has to take a two-track approach to the matter: one to address security issues based on the South Korea-US alliance, and the other to deal with the economy under the principle of multilateral cooperation."

He also highlighted the importance of respect and trust when it comes to trilateral cooperation between South Korea, US and Japan.

"The South Korea-US-Japan security alliance is very important, but the alliance between allies, especially regional security cooperation, is not consolidated solely on the military aspect. Understanding and cooperation in cultural, diplomatic, and historical backgrounds should be the basis of the alliance," said Yang.

Seoul-Tokyo relations have plunged to their lowest ebb over history issues that include Japan's forcing of Korean men and women into free labor and sexual slavery during World War II.

"South Korea and Japan's past problems are not for the United States to intervene in. If the US must intervene, it should do so only to the extent of playing the role of a fair mediator. However, if the US uses the situation to seek immediate conveniences for itself, it will lead to a situation where it may seriously lose the trust of the Korean people," said Yang. (Yonhap)