Trump rocked South Korea in the past weeks by indicating that he will charge Seoul for the deployment of a Terminal High Altitude Area Defense  battery priced at more than US$1 billion, a remark that contradicts the terms of the deployment agreement forged between Park and former US President Barack Obama.

Trump also warned that their five-year-old free trade deal will also be renegotiated, which, if actualized, is likely to inflict about $17 billion in losses on South Korean exports to America, according to the Korea Economic Research Institute.

Meanwhile, Trump further fueled the fears of "Korea passing" here, by skipping South Korea in his telephone talks for policy coordination following North Korea's launch of a new ballistic missile on April 5, which only included Japanese Prime Minister Shinzo Abe and Chinese President Xi Jinping.

The Korea passing has recently made headlines here for fears that South Korea would be made to sit out the US-led efforts to deal with the rising tensions on the Korean Peninsula and to eventually denuclearize North Korea.

South Korea was again taken aback by Trump's historically wrong remark that Korea was once part of China. The mention he made after his summit with China sparked skepticism over the US president's understanding of the Asian ally and his commitment to a well-tuned alliance with Seoul.

"South Korea's next president is likely to face a situation in which diplomacy takes a front seat in comparison with international politics for a considerable period of time as the world order is tilted toward 'power politics' away from the rule-based one as a result of Trump and Xi Jinping," said former Ambassador to Romania Im Han-taek, now a visiting professor at Hankuk University of Foreign Studies.

"Rebuilding mutual trust between South Korea and the US as allies should first be rushed through diplomacy between the top leaders, and South Korea should also waste no time in joining the cockpit of North Korean policy making now dominated by the US and China," he noted.

With China, the incoming president also has an unprecedentedly difficult task to stop Beijing's retaliatory policies over the THAAD deployment here, which the country said is intended to spy on the Chinese military despite the South Korea-US insistence that it only aims to intercept North Korean missiles.

In the most crushing of its continued retaliations, China has banned its tour agencies from selling tours to South Korea since March, dealing a heavy blow to Seoul's relations with Beijing, its biggest trading partner.

The South Korea-Japan relations have also remain entangled in a long-running history row over the imperial Japanese army's sexual enslavement of Korean women during the Japanese colonial control of the peninsula from 1910-45.

In December 2015, the Park administration signed what was once hailed as a landmark deal to end the history row once and for all, but the bilateral relationship remains stuck in disagreement over the execution of the agreement.

Presidential front-runner Moon Jae-in, who had 38 percent of voters' support in the last poll before the election day released Wednesday, campaigned to revisit the THAAD deployment and the "comfort women" deal with Japan if he wins the presidency.

In 2nd place, Ahn Cheol-soo, a centrist who garnered 20 percent, said he will retain THAAD while opening a renegotiation with Japan.

Conservative Hong Joon-pyo in third place with 16 percent is in support of the defense system but also said the deal with Japan could be subject to renegotiation. (Yonhap)