"Specific details have yet to be determined, but South Korea is fine-tuning the visit with Japan to take place within this month", one of the sources noted.
Earlier Russia's United Nations ambassador said North Korea should stop its missile and nuclear tests but also called on Washington to cancel military exercises with South Korea planned for December as it would "inflame an already explosive situation".
Under the previous administration of impeached President Park Geun-hye, Seoul reached a deal with Japan on December 2015 to end the so-called comfort women feud once and for all in exchange for Japan's state fund to support the Korean victims.
"The dictator of North Korea made a decision yesterday that brings us closer to war, not farther from it", she said.
President Donald Trump tweeted that he spoke with Chinese President Xi Jinping about Pyongyang's "provocative actions", and he vowed that "additional major sanctions would be imposed on North Korea today". We do think they could do more with the oil.
But her call for nations to "cut off all ties with North Korea" was rejected by Moscow, with foreign minister Sergei Lavrov saying Russian Federation saw the proposal "negatively". "We are stuck. We have to adapt to North Korea as a nuclear power, and we will actually".
Trump has pledged more sanctions in response to the latest test and, at an emergency U.N. Security Council meeting late Wednesday, the United States warned North Korea's leadership would be "utterly destroyed" if war were to break out.
A White House statement said Trump and Moon reiterated their strong commitment to enhancing the deterrence and defense capabilities of the U.S.
U.S. sanctions against North Korea were bolstered last week after the Trump administration declared North Korea a state sponsor of terrorism. -South Korea alliance and added: "Both leaders reaffirmed their strong commitment to compelling North Korea to return to the path of denuclearization at any cost".
North Korea tested a new ICBM, which Pyongyang claims is capable of reaching any target in the continental United States.
It has said its weapons programs are a necessary defense against USA plans to invade.
Russian Foreign Minister Sergey Lavrov said on Friday that a U.S. threat to destroy North Korea in the event of a war was "a bloodthirsty tirade" and military action against Pyongyang would be a big mistake. But China has refused to turn off its pipeline shipping crude to the North Beijing fears that taking tougher actions could cause the regime to collapse, triggering a refugee crisis across its border with the North and eliminating a strategic buffer separating China from the USA military in South Korea.