Trump and Moon "agreed that concrete actions, not words, will be the key to achieving permanent denuclearization of the Korean peninsula, and President Trump reiterated his intention to meet with North Korean leader Kim Jong Un by the end of May", the White House said.
Im added Moon may meet Trump after the inter-Korean summit but before Trump's planned summit with Kim in May.
Margot Wallstrom spoke to reporters on Friday after she met Ri Yong Ho in Stockholm for a second consecutive day.
The reactor could be used to produce weapons-grade plutonium, but North Korea is believed to already have enough fissile material for multiple nuclear bombs, according to Joshua Pollack, a senior research associate at the Middlebury Institute of International Studies at Monterey. Details about their talks were not revealed.
At a news conference in Washington last week, Mr Trump thanked Swedish Prime Minister Stefan Lofven for helping American detainees in North Korea and particularly in securing the release of USA student Otto Warmbier a year ago.
"The Swedish foreign ministry has said talks "will focus on Sweden's consular responsibilities as a protecting power for the United States, Canada and Australia", but also will also address the security situation on the Korean Peninsula".
Supreme Court's stern warning for news channels, websites
I have myself rebuffed all attempts to gag the media, but we do expect media, especially electronic media, to become more responsible.
North Korean Foreign Minister Ri Yong Ho gets on a auto on his arrival at the Beijing International airport in Beijing, Thursday, March 15, 2018.
From Washington, Trump called his South Korean counterpart Moon Jae-in, whose government last week passed an apparent summit invitation to Trump from Kim.
South Korean-born Yun, a strong advocate for engagement with Pyongyang, led contact with North Korea and quietly pursued direct diplomacy since taking his post under former President Barack Obama in 2016.
Yun, who stepped down as USA special representative for North Korea policy, said he welcomed the planned May meeting between Trump and Kim.
In the past, that has meant Washington would have to withdraw all of its troops from South Korea, a condition no US president has been willing to consider.
There's a whirlwind of speculation surrounding the what, when and where of an upcoming potential summit between Kim Jong Un and Donald Trump.