READ MORE: North Korea says it won’t bow down to ‘gangster-like’ U.S. on denuclearizationWATCH: Pompeo sharpens tone on North Korea 1:30 Pompeo sharpens tone on North Korea Pompeo sharpens tone on North Korea Speaking to members of the U.S.-Vietnamese business community in Hanoi, Pompeo said Vietnam’s experience since the normalization of relations with the U.S. in 1995 should be proof for North Korea that prosperity and partnership with the U.S. is possible after decades of conflict and mistrust. “We know it is a real possibility because we see how Vietnam has traveled this remarkable path,” Pompeo said.“The fact that we are cooperating — and not fighting — is proof that when a country decides to create a brighter future for itself alongside the United States, we follow through on American promises,” he said, repeating President Donald Trump’s pledge to help improve North Korea’s economy and provide it with security assurances in return for Kim giving up nuclear weapons. “In light of the once-unimaginable prosperity and partnership we have with Vietnam today, I have a message for Chairman Kim Jong Un: President Trump believes your country can replicate this path.”WATCH: Pompeo sends message to Kim Jong Un, says ‘miracle could be yours’ if country replicates Vietnam’s path 1:14 Pompeo sends message to Kim Jong Un, says ‘miracle could be yours’ if country replicates Vietnam’s path Pompeo sends message to Kim Jong Un, says ‘miracle could be yours’ if country replicates Vietnam’s path “It’s yours if you’ll you seize the moment. This miracle can be yours. It can be your miracle in North Korea as well,” Pompeo said.The comments came after Pompeo had earlier Sunday in Tokyo brushed aside North Korea’s accusation that the U.S. was making “gangster-like” denuclearization demands of the North. He maintained that his third visit to North Korea on Friday and Saturday had produced results. But he also vowed that sanctions would remain until Pyongyang follows through on Kim’s pledge to get rid of his atomic weapons.WATCH: North Korea calls talks with Pompeo ‘regrettable,’ contradicting U.S. Secretary of State’s comments 1:18 North Korea calls talks with Pompeo ‘regrettable,’ contradicting U.S. Secretary of State’s comments North Korea calls talks with Pompeo ‘regrettable,’ contradicting U.S. Secretary of State’s comments Pompeo downplayed a harshly critical North Korean statement issued after the talks in which the country’s foreign ministry bashed hopes for a quick deal and attacked the U.S. for making unreasonable and extortionate demands aimed at forcing it to abandon nuclear weapons. The statement was sure to fuel growing skepticism in the U.S. and elsewhere over how serious Kim is about giving up his nuclear arsenal. Undeterred by a blistering rebuke of his efforts to forge a denuclearization deal with North Korea, U.S. Secretary of State Mike Pompeo on Sunday appealed for North Korea ’s leadership to follow Vietnam ’s path in overcoming past hostilities with the United States.Pompeo called on North Korean leader Kim Jong Un to replicate Vietnam’s “miracle” of economic growth by improving ties with the U.S., vowing that America keeps its promises with former foes.Speaking to members of the U.S.-Vietnamese business community in Hanoi, Pompeo said Vietnam’s experience since the normalization of relations with the U.S. in 1995 should be proof for North Korea that prosperity and partnership with the U.S. is possible after decades of conflict and mistrust. “We know it is a real possibility because we see how Vietnam has traveled this remarkable path,” Pompeo said.“The fact that we are cooperating — and not fighting — is proof that when a country decides to create a brighter future for itself alongside the United States, we follow through on American promises,” he said, repeating President Donald Trump’s pledge to help improve North Korea’s economy and provide it with security assurances in return for Kim giving up nuclear weapons. “In light of the once-unimaginable prosperity and partnership we have with Vietnam today, I have a message for Chairman Kim Jong Un: President Trump believes your country can replicate this path.”“It’s yours if you’ll you seize the moment. This miracle can be yours. It can be your miracle in North Korea as well,” Pompeo said.The comments came after Pompeo had earlier Sunday in Tokyo brushed aside North Korea’s accusation that the U.S. was making “gangster-like” denuclearization demands of the North. He maintained that his third visit to North Korea on Friday and Saturday had produced results. But he also vowed that sanctions would remain until Pyongyang follows through on Kim’s pledge to get rid of his atomic weapons.Pompeo downplayed a harshly critical North Korean statement issued after the talks in which the country’s foreign ministry bashed hopes for a quick deal and attacked the U.S. for making unreasonable and extortionate demands aimed at forcing it to abandon nuclear weapons. The statement was sure to fuel growing skepticism in the U.S. and elsewhere over how serious Kim is about giving up his nuclear arsenal.

“If those requests were gangster-like, the world is a gangster,” Pompeo said, noting that numerous U.N. Security Council resolutions have demanded that the North rid itself of nuclear weapons and end its ballistic missile program. “People are going to make certain comments after meetings. If I paid attention to the press, I’d go nuts and I refuse to do that.” Tweet This

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After meeting with his Japanese and South Korean counterparts in Tokyo, Pompeo said his two days of talks in Pyongyang had been productive and conducted in good faith. But following the stinging commentary from the North, he allowed that much work remains.

READ MORE: Trump reportedly sent Kim Jong Un an Elton John CD with the song ‘Rocket Man’

“The road ahead will be difficult and challenging, and we know critics will try to minimize the work that we have achieved,” he said. He added that his two days of talks with senior North Korean officials had “made progress” and included a “detailed and substantive discussion about the next steps towards a fully verified and complete denuclearization.”

Those include the formation of a working group to determine exactly how North Korea’s denuclearization will be verified and a Thursday meeting with Pentagon officials to discuss the return of remains of American soldiers killed during the Korean War.

Pompeo sought to dispel suggestions that the Trump administration has backed down from demanding the complete, verifiable and irreversible dismantlement of the North’s nuclear weapons. He said North Korea understood that denuclearization must be “fully verified” and “final.”

WATCH: North Korea calls talks with Pompeo ‘regrettable,’ contradicting U.S. Secretary of State’s comments

1:18 North Korea calls talks with Pompeo ‘regrettable,’ contradicting U.S. Secretary of State’s comments North Korea calls talks with Pompeo ‘regrettable,’ contradicting U.S. Secretary of State’s comments

South Korean Foreign Minister Kang Kyung-wha said that North Korea had balked at a written pledge for “complete, verifiable and irreversible denuclearization” for historical reasons but stressed that the goal remained the same whether that exact phrase was used. Fully verified, final denuclearization “isn’t any softer in stating our shared goal of complete denuclearization,” she said.

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Despite what he described as progress, Pompeo said the results so far did not warrant any easing of sanctions, which he said would be enforced “with vigor” until North Korea follows through with denuclearization.

After Trump’s historic summit with Kim in Singapore last month, the president declared the North was no longer a threat and would hand over the remains of American soldiers. Yet three weeks later, the two sides were still divided on all the issues, including exactly what denuclearization means and how it might be verified. The promised remains have yet to be delivered.

READ MORE: North Korea building new submarine capable of launching ballistic missiles, South Korean lawmaker says

WATCH: Pompeo says progress made on timeline of North Korea’s denuclearization

1:18 Pompeo says progress made on timeline of North Korea’s denuclearization Pompeo says progress made on timeline of North Korea’s denuclearization

And just hours after Pompeo arrived in Tokyo from Pyongyang on Saturday, the North blasted the new talks, saying they had been “regrettable.”

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In a statement carried by the North’s official Korean Central News Agency, the foreign ministry said the outcome of Pompeo’s talks with senior official Kim Yong Chol was “very concerning” because it has led to a “dangerous phase that might rattle our willingness for denuclearization that had been firm.”

“We had expected that the U.S. side would offer constructive measures that would help build trust based on the spirit of the leaders’ summit … we were also thinking about providing reciprocal measures,” it said. “However, the attitude and stance the United States showed in the first high-level meeting (between the countries) was no doubt regrettable. Our expectations and hopes were so naive it could be called foolish.”

It said the North had raised the issue of formally ending the Korean War, which concluded with an armistice and not a peace treaty, but the U.S. came up with a variety of “conditions and excuses” to delay a declaration. It downplayed the significance of the United States suspending its military exercises with South Korea, something trumpeted by Trump after the summit as a success, by saying it made a larger concession by blowing up the tunnels at a nuclear test site.