Democrats also called on the White House to engage Congress throughout the diplomatic process, and stressed that were the Trump administration to start "veering off course" and sign an unsatisfactory deal, Republican and Democratic lawmakers would act.
"We are actively preparing for the June 12 summit between the president and the North Korean leader", White House spokesperson Sarah Sanders said.
Meanwhile Trump has promised to "transform" the rogue state after a meeting with the dictator's right-hand man, Kim Yong Choi.
With just one week left until the Singapore summit between President Trump and Kim Jong Un, National Security Adviser John Bolton is being carefully excluded from everything surrounding the event, including last week's visit by Kim Yong Chol.
Mr Trump, who had previously cancelled the summit, abruptly announced the meeting was back on.
Topping their demands is the elimination of "all nuclear, chemical and biological weapons from North Korea".
Bolton's actions have now reportedly cost him his role in organizing the North Korea summit, which is scheduled to take place in Singapore on June 12 at 9 a.m. local time.
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You've got to know he's going to end up with 30 points and a triple-double and all that stuff because he's that good. Curry had a slow start from the perimeter, making just one of his first five attempts in the first quarter.
While Trump has made gestures toward human rights issues in North Korea, those efforts have largely been created to increase pressure on the country's government.
Rodman, who fancies himself a sports ambassador to North Korea, said that he did not "want to take all the credit" for laying the groundwork for the summit.
The Singapore government has said police would make stricter checks of people and personal belongings and items such as public address systems and remotely piloted aircraft system would be prohibited in the area.
Russian Federation said it did not want to interfere in the diplomatic efforts of the US.
Trump aims to persuade the North Korean dictator to give up his country's nuclear arsenal in exchange for relief from USA economic sanctions.
Gen Kim Yong-chol's visit came a day after he met US Secretary of State Mike Pompeo in NY, who described their talks of denuclearisation as "substantive".
Trump has given top priority to the full denuclearization of North Korea.
Former US officials and analysts say that if the meeting produces a peace declaration, this could give Trump a big headline-grabbing, made-for-TV moment on the world stage.
Syrian president Bashar al-Assad plans to pay a state visit to North Korea, the North's official news agency says.