The Washington Post said Trump's personal involvement in the White House's deliberations over the world's most serious and vexing security situation "has placed a president who considers himself a master dealmaker into the most fraught faceoff of his 71 years".

"The deal with North Korea is very much in the making and will be, if completed, a very good one for the World. Time and place to be determined," Trump said in a tweet, as experts and analysts scrambled to decipher the unexpected and surprising decision of the president.

"A breakthrough that would reduce Pyongyang's nuclear threat would be a legacy-defining achievement. A stalemate that gives Kim a photo-op for nothing in return could fracture US alliances and be seen as a devastating embarrassment," the daily said.

According to the Wall Street Journal, Trump has stood the traditional diplomatic model on its head.

"Casting aside years of protocol, the president agreed to a summit with Mr Kim before any of his aides had even sat down with a North Korean representative to clarify precisely where Pyongyang stands on fundamental nuclear issues," it said.

And for the New York Times, the high-level diplomatic encounter is so risky and seemingly far-fetched that some of Trump's aides believe it will never happen.

"Several officials said on Friday that the United States still needed to establish direct contact with North Korea to verify the message from Mr Kim that was conveyed by South Korean envoys to Mr Trump on Thursday. They warned that Mr Kim could change his mind or break the promises he made about halting nuclear and missile tests during talks," the daily said.

Senator Dan Sullivan, member of the Senate Armed Services Committee, said it is clear that the maximum global pressure campaign US has been focused on for months under the leadership of the Trump administration - US sanctions mandated by Congress, additional sanctions authorised by the UN Security Council, the development of credible military options, and pressuring China to do much more regarding North Korea – is having a real impact and clearly starting to bite.

"As we move forward with the objective of the complete denuclearisation of the Korean Peninsula, staying very closely aligned with our allies in the region – especially the Republic of Korea and Japan – will be critical, along with the continuation of the maximum pressure campaign, US-Republic of Korea joint military exercises, and importantly the stationing of US military forces on the Korean Peninsula," Sullivan said.

House Democratic Whip Steny H Hoyer welcomed the initiative from South Korea and hope it can lead to a peaceful resolution of the North Korean nuclear crisis.

"However, we have to be very careful and skeptical of any overtures by North Korea, given its history of failing to deliver on its commitments. The president and our negotiators must approach this development with due caution and openness, and any talks should be based on realistic expectations of what can be negotiated and verified," he said.

Senator Mark R Warner, vice chairman of the Senate Select Committee on Intelligence, said that diplomacy is the right path forward to deal with North Korea, but at the same time, due to Pyongyang's history of obfuscation and international defiance, the United States must proceed with caution.

"I am deeply concerned that the White House has not laid the necessary diplomatic groundwork and coordination for direct talks with North Korea. Even President Trump's own secretary of state appeared to be taken aback by this announcement," he said.

"Trump's record of cosying up to authoritarian governments, his consistent failure to appoint, empower or value the expertise of professional diplomats, and his overall lack of focus on critical details also give me pause. The administration must go into any meeting with a plan to ensure that negotiations with Kim Jong-un produce real results, not a photo-op that lends legitimacy to North Korea's murderous regime," Warner said.