The US would be "prepared to work with North Korea to achieve prosperity on the par with our South Korean friends", he told reporters on Friday.
The announcement came from United States president Donald Trump, who posted it on his twitter account.
She said the US troop presence in the South for the past 65 years has played a "crucial role for deterrence", peace and stability on the Korean peninsula.
Vice President Mike Pence, Secretary of State Mike Pompeo, other top officials and first lady Melania joined the president in the celebration in the wee hours of Thursday morning at Joint Base Andrews near Washington. Kim has said that North Korea now has the capability to strike the continental United States.
"We had good conversations, conversations that involve deep complex problems, challenges, strategic decisions that chairman Kim has before him", Pompeo said.
Kim declared his nuclear forced as complete in December, following the country's most powerful nuclear test to date in September and also three flight tests of intercontinental ballistic missiles created to reach the US mainland.
He said its policy was now "to concentrate all efforts into economic progress", but stressed that this had nothing to do with worldwide sanctions imposed on the country.
He described his conversations with Kim as "warm" and said both had tried "our best to make sure that we were communicating clearly and had shared understanding about what our mutual objectives were".
Japan, China and South Korea agreed in a trilateral leaders' summit on Wednesday in Tokyo that they will work toward the peninsula's denuclearisation in a rare show of unity.
This report came after the US Secretary of State Mike Pompeo, visited North Korea and returned with three captive Americans.
South Korean Foreign Minister Kang Kyung-wha stressed that sanctions against Pyongyang would not be lifted until it had taken concrete steps to denuclearise. "We talked about the fact that America has often in history had adversaries who we are now close partners with and our hope that we can achieve the same with respect to North Korea".
As of now, only one day has been kept for the meeting between Trump and Kim Jong-un, he said, adding that planning was still in progress.
When asked what the President meant when he said on Thursday that the summit could be scuttled, Mr Shah said: "Well, we have over a month, right?"
It has one foot in the East and one in the West, is ultra-modern, secure and sometimes mocked as being a little boring - Singapore was the safe pick for a historic first meeting between the unpredictable leaders of the USA and North Korea. "It will make it more hard for Kim Jong Un to deny inspections now that he has placed them on the table".