WASHINGTON/SEOUL (Reuters) - North Korean state media acknowledged a fruitless summit between its leader Kim Jong Un and U.S. President Donald Trump for the first time on Friday, saying people were blaming the United States for the lack of an agreement.

Trump however was open to more talks with North Korea aimed at North Korea’s denuclearization, his national security adviser said, despite reports it is reactivating parts of its missile program.

“The public at home and abroad that had hoped for success and good results from the second DPRK-U.S. summit in Hanoi are feeling regretful, blaming the U.S. for the summit that ended without an agreement,” Rodong Sinmun, the newspaper of the North’s ruling Workers’ Party, said in a commentary.

North Korea’s official name is the Democratic People’s Republic of Korea.

The newspaper used fiery rhetoric against Japan, accusing it of being “desperate to interrupt” relations between Pyongyang and Washington and “applauding” the breakdown of the summit.

After the summit collapsed, U.S. ally Japan focused on scepticism about the future of the nuclear diplomacy given how the two sides failed to bridge the gap.

New activity has been detected at a factory that produced North Korea’s first intercontinental ballistic missiles (ICBMs) capable of reaching the United States, South Korea’s JoongAng Ilbo and Donga Ilbo newspapers reported, citing lawmakers briefed by the National Intelligence Service.

This week, two U.S. think-tanks and Seoul’s spy agency said North Korea was rebuilding its Sohae rocket launch site, prompting Trump to say he would be “very, very disappointed” in North Korean leader Kim Jong Un if it were true. The think tanks said on Thursday that they believed the launch site was operational again.

White House National Security Adviser John Bolton, who has argued for a tough approach to North Korea, said Trump was still open to further talks.

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“The president’s obviously open to talking again. We’ll see when that might be scheduled or how it might work out,” he told Fox News, adding it was too soon to make a determination on the reports of the North Korean activity.

“We’re going to study the situation carefully. As the president said, it would be very, very disappointing if they were taking this direction.”

The Vietnam summit on Feb. 27-28 collapsed over differences about how far North Korea was willing to limit its nuclear program and the degree of U.S. willingness to ease economic sanctions.

Trump, eager for a big foreign policy win on North Korea, which has eluded his predecessors for decades, has repeatedly stressed his good relationship with Kim. He went as far late last year as saying they “fell in love,” but the bonhomie has failed to bridge the wide gap between the two sides.

‘NO COMMITMENT YET’

U.S. Secretary of State Mike Pompeo said on Monday he was hopeful he would send a delegation to North Korea for more talks in the next couple of weeks, but that he had received “no commitment yet.”

A senior State Department official told reporters on Thursday that Washington was keen to resume talks as soon as possible, but North Korea’s negotiators needed to be given more latitude than they were ahead of the summit.

He said no one in the U.S. administration advocated the incremental approach that North Korea has been seeking and the condition for its integration into the global economy, a transformed relationship with the United States and a permanent peace regime, was complete denuclearization.

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“Fundamentally, where we really need to see the progress, and we need to see it soon, is on meaningful and verifiable steps on denuclearization. That’s our goal and that’s how we see these negotiations picking up momentum.”

The official, who did not want to be identified, said the U.S. side still saw North Korea’s complete denuclearization as achievable within Trump’s current term, which ends in January 2021.

While the official said he would “not necessarily share the conclusion” that the Sohae site was operational again, any use of it would be seen as “backsliding” on commitments to Trump.

MISSILE FACTORY

South Korean spy chief Suh Hoon told lawmakers in Seoul that cargo vehicles were spotted moving around a North Korean ICBM factory at Sanumdong recently, the JoongAng Ilbo reported.

The paper also quoted Suh as saying North Korea had continued to run its uranium enrichment facility at the main Yongbyon nuclear complex after Trump and Kim’s first summit in Singapore last June.

Separately, Washington’s 38 North and Center for Strategic and International Studies think-tanks reported on Thursday that the Sohae site, which Kim pledged in Singapore to dismantle, appeared to be operational again after rebuilding work that began days before the Hanoi summit.

“The rebuilding activities at Sohae demonstrate how quickly North Korea can easily render reversible any steps taken towards scrapping its Weapons of Mass Destruction program with little hesitation,” CSIS said.

It called the action “an affront” to Trump’s diplomatic strategy that showed North Korean pique at his refusal to lift sanctions.

Some analysts see the work as aimed at pressing Washington to agree to a deal, rather than as a definite move to resume tests.

A U.S. government source, who did not want to be identified, said North Korea’s plan in rebuilding the site could have been to offer a demonstration of good faith by conspicuously stopping again if a summit pact was struck, while furnishing a sign of defiance or resolve if the meeting failed.

On Wednesday, Bolton warned of new sanctions if North Korea did not scrap its weapons program.

Despite his sanctions talk, there have been signs across Asia that the U.S. “maximum pressure” sanctions campaign against North Korea has sprung leaks.

In a new breach, three South Korean companies were found to have brought in more than 13,000 tons of North Korean coal, worth 2.1 billion won ($2 million) since 2017, South Korea said.