Moon will hold a summit meeting with President Donald Trump in Washington on April 11 to discuss North Korea and other alliance issues, the White House said on Friday.
Ahead of the Trump-Moon summit, South Korea said it was dispatching its foreign and defense ministers, among other senior officials, for meetings in Washington.
North Korea has nearly completed rebuilding a long-range rocket site it had promised to close, Seoul lawmakers told reporters Friday after a closed-door meeting with South Korean intelligence officials.
It will be their first meeting since the breakdown of last month's summit between Trump and North Korean leader Kim Jong-un in Hanoi.
The much-anticipated second meeting between the two leaders was supposed to build on their historic first summit in Singapore in June previous year.
"Ultimately", he said, positive results will depend on "whether we can convince him that it's the right strategic direction for him and for his country".
The breakdown of that summit put Moon, a liberal who has shuttled between Washington and Pyongyang, in a hard position on how to further engage North Korea and facilitate the nuclear diplomacy.
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Citing analyses of commercial satellite imagery, many civilian experts in the US have previously given similar assessments on the North's Tongchang-ri launch facility and the Yongbyon nuclear complex.
Pyongyang said it had proposed dismantling the Yongbyon complex - a sprawling site covering multiple different facilities - in exchange for the lifting of economic sanctions that have strangled and isolated the North.
Each side has blamed the other, with the United States saying North Korea demanded too much sanctions relief and Pyongyang faulting Washington for rejecting its promises to reduce its nuclear programme.
North Korea recently withdrew its entire staff at a frontline liaison office with South Korea before sending some of them back to the office.
The lack of progress with North Korea has become a domestic problem for Mr Moon, who has staked much of his political capital on improving relations with Pyongyang.
Also Friday, South Korea received the first two of the 40 F-35A fighter jets that it has agreed to buy from Lockheed Martin by 2021.
He claimed that the conversation the two had at the time revolved around trading the North's nuclear program for a "brighter future", but added that at present, "we have not seen them take a step in that direction yet". Some experts say North Korea still hopes to keep diplomacy with the United States alive.