The president reminded critics that since he first agreed to meet Kim Jong-un, North Korea stopped testing nuclear weapons, paused missile launches, and returned American hostages to the United States.
But he added: "In the end, that doesn't matter".
"Trump is likely to declare the summit a victory irrespective of the outcome, but if the two sides fail to reach a common understanding of denuclearisation it will put at risk any process that the summit kicks off", he said.
On May 10, Trump announced that he would meet Kim on June 12 in Singapore. Kim spent the day mostly out of view - until he left his hotel for a late-night tour of Singapore sights, including the Flower Dome at Gardens by the Bay, billed as the world's biggest glass greenhouse.
The Trump administration will only accept complete denuclearisation of the North, Mr Pompeo stressed.
In the lead up to the summit, North Korea, however, has rejected any unilateral nuclear disarmament, and its reference to denuclearisation of the peninsula has historically meant it wants the United States to remove its "nuclear umbrella" protecting South Korea and Japan, which it sees as a threat.
North and South Korea remain technically at war after the 1950-53 conflict ended in an armistice that Seoul's then leader refused to sign and divided the peninsula along the Demilitarised Zone. The Kim regime has said that it may be willing to tolerate the presence of USA troops in South Korea, a significant departure from its previous stance on the issue.
But he has since lowered expectations, backing away from an original demand for North Korea's swift denuclearisation.
Pointing out that the Rodong Sinmun goes simultaneously out to the global and domestic audience, NK Pro analyst Fyodor Tertitskiy says that the article will send "quite a positive message because the North Korean leadership at least state they are prepared to learn from foreign nations' experience and that they are focused on achieving economic prosperity".
Trump has said he'll know within minutes whether a deal can be made.
In extraordinary scenes, Kim smiled as he walked and waved towards the crowd of tourists, families and media as a "woo" went up. Mr Kim is reported to be flying out even earlier, at 14:00 local time (6pm NZT). "China will be more than happy to facilitate that strategic transition, but a precondition to doing that is a better North Korea-US relationship".
Close US ally Japan has urged Trump to bring up the decades-old issue of its citizens abducted in 1970s and 1980s to train Pyongyang's spies in Japanese language and customs. Two weeks later, however, he cancelled the meeting in a letter to Kim, citing "open hostility" from North Korea.
Retired American professional basketball player Dennis Rodman speaks to the press as he arrives at Changi International airport ahead of US-North Korea summit in Singapore on June 11, 2018. Kim then called Trump a "mentally deranged USA dotard" and a "frightened dog".
Talks proceeded at multiple levels, including logistical discussions to allay Kim's fears of being deposed while traveling further afield than he ever has before as the country's leader. In that first meeting they'll be joined only by translators, a break from standard practice of having at least one aide present for high-stakes huddles.
The US is also concerned about the proliferation of North Korea's weapons and the infrastructure supporting its nuclear programme, and will want those issues addressed as part of any deal. "If Trump gets something about this, it will boost his agenda".