Trump cancelled the on-off North Korea summit in late May, blaming the country's "tremendous anger and open hostility".
She refused to discuss the possibility that South Korean President Moon Jae-in will join Trump and Kim in Singapore for such a declaration.
Russian President Vladimir Putin has praised his U.S. counterpart Donald Trump for his "brave and mature" decision to go ahead with meeting with Kim Jong-un.
Trump described a giant letter he received from Kim as "a very nice letter. a very interesting letter".
A day earlier, a North Korean official insulted Vice President Mike Pence and threatened the USA with a "nuclear showdown".More news: Asus ROG gaming smartphone with 90Hz display refresh rate, overclocked CPU launched
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"And the President will make his views known directly to him when we're in Singapore, and our focus will continue to be on denuclearisation", Sanders said.
In a letter to Trump earlier this week, several Democratic lawmakers said that they would not support an agreement with North Korea unless its provisions included the complete disarmament of Pyongyang's nuclear and ballistic missile programs.
North Korea is reportedly interested in creating a step-by-step plan for denuclearization and Trump reportedly said he would be flexible, though he's been advised not to compromise.
Mr Trump and Mr Kim's highly anticipated meeting is scheduled for 9am local time on June 12 after a flurry of on-again-off-again action.
The minister, who will be accompanied by foreign ministry officials, will also meet the North's ceremonial president Kim Yong Nam.
"They have announced this engagement with the U.S.is now a part of their national narrative but I don't think it's one based on weakness or a desire to get economic assistance", he told the same hearing.
"Through these series of meetings, I'm confident we're moving in the right direction.It could be nothing short of tragic to let this opportunity go to waste", Pompeo said.