In his first discussion with the new South Korean leader, Chinese President Xi Jinping asserted that he doesn't want South Korea to deploy a USA missile system, according to the BBC.
But Moon also has to navigate a complex web of regional issues. But the system has led to a deep schism in relations between Beijing and Seoul, prompting widespread boycotts in China of popular South Korean brands.
"We hope for Russian Federation to play a constructive role in order for North Korea to stop with its nuclear provocations and go the way of denuclearisation", Moon was cited as saying to Putin in the 20-minute conversation.
That contrasted with its one-sentence Korean-language report of the election of Mr Moon's conservative predecessor Park Geun-Hye in 2012, which did not mention her name or her support.
But ties have plummeted.
While South Korea, China and Japan all worry about North Korea, ties between South Korea and China have been strained by South Korea's decision to install a United States anti-missile system in defence against the North.
"I am well aware of the concern and fear of the Chinese about the THAAD deployment", Moon was quoted as saying when Xi explained the Chinese stance on the matter.
Xi congratulated Moon on his election and the leaders agreed to exchange special envoys as soon as possible, Yoon said.
During their 25-minute conversation, Abe told Moon that he would like to "properly manage the bilateral relationship" in light of the accord.
"How to respond to North Korea.is an urgent issue".
Moon has said he would "go to Pyongyang if conditions are met" during his inaugural address, and had proposed the reopening of a jointly operated factory park in the right circumstances.
Moon told Abe that most Koreans could not accept the agreement, according to the Blue House, while Japan's top government spokesman Yoshihide Suga said Abe told him it was "extremely important" to implement it. Beijing sees the system as a threat to its own security.
North Korea has been working to develop a nuclear-tipped missile capable of reaching the United States, presenting Trump with perhaps his most pressing security issue.
Tensions have been running high with rhetoric intensifying on both sides, but Trump recently softened his posture, saying he would be "honoured" to meet the North's leader Kim Jong-Un.
Both the US and South Korea are keen on dismantling the nuclear program of Kim Jong Un and hence, are open to maintaining the sanctions on North Korea already laid in place by Trump's administration.
The North's vice foreign minister Han Song-Ryol briefed foreign diplomats in Pyongyang Thursday on the alleged plot, calling it "the most vicious challenge and a declaration of war".