Seoul is willing to resume inter-Korean economic cooperation if it would help to hasten Pyongyang's denuclearisation, President Moon Jae-in said in a phone call with Donald Trump on Tuesday.
The US President and North Korean leader Kim Jong Un are due to meet in Hanoi for a much-anticipated second summit on February 27-28 following their landmark first meeting in Singapore last year.
Those talks, the first-ever between the leaders of the US and North Korea, produced a vaguely-worded document in which Kim pledged to work towards "the denuclearisation of the Korean peninsula".
But progress has since stalled with the two sides disagreeing over what it means and analysts say tangible progress on denuclearisation will be needed if the talks are to avoid being dismissed as "reality TV".
In his move to support the US and its effort to "establish permanent peace" on the Korean peninsula, Moon said Seoul is willing to "share the burden", carrying out joint economic projects with the North including reconnecting railways across the border.
"(President Moon) said (the joint economic projects) are some of the ways for South Korea to lessen the burden of the US," Seoul's presidential Blue House spokesperson Kim Eui-kyeom said in a statement.
Moon said Seoul could use these measures "to support North Korea as it goes through its denuclearisation process", Kim added.
In November, the Blue House said the UN Security Council granted a sanctions exemption for the two Koreas to jointly conduct a survey on connecting railways.
Experts, however, have warned that rail links could take decades and will require huge investment.
Security allies Seoul and Washington have at times pursued divergent approaches toward Pyongyang, with Moon pursuing engagement while the United States insists pressure must be maintained until the North denuclearises.
But Trump told Moon on Tuesday that US-South Korea relations are "better than ever", according to spokesman Kim.