SAN FRANCISCO / TOKYO (BLOOMBERG, REUTERS) - North Korea could be preparing to launch a missile or rocket in the near future, according to satellite images of activity in the country, US radio network NPR reported, while the country's state media said the world is blaming the US for ending the Hanoi summit without an agreement.

The images were taken on Feb 22 at the Sanumdong facility near Pyongyang, where North Korea has assembled some of its intercontinental ballistic missiles and satellite-launching rockets, NPR reported.

They show trucks and cars parked nearby, while rail cars sit in a yard, where two cranes are erected, it said. The pictures were taken by DigitalGlobe and shared exclusively with NPR.

"When you put all that together, that's really what it looks like when the North Koreans are in the process of building a rocket," Jeffrey Lewis, director of the East Asia Nonproliferation Project at the Middlebury Institute of International Studies at Monterey, told NPR. Mr Lewis said it was impossible to know if North Korea is preparing a military missile or a space rocket.

The release of the images comes after US President Donald Trump abruptly ended a summit with Kim Jong Un in Vietnam late last month after the US president said the North Korean leader asked for all US sanctions to be lifted in exchange for the dismantling of the country's main nuclear complex.

'FEELING REGRETFUL'

"The public at home and abroad that had hoped for success and good results from the second DPRK-US summit in Hanoi are feeling regretful, blaming the US for the summit that ended without an agreement," Korea Central News Agency reported, citing a commentary in the Rodong Sinmun newspaper.

Mr Trump said on Friday (March 8) he would be disappointed if Pyongyang were to resume weapons testing and reiterated his belief in his good relationship with Mr Kim despite the collapse of their second summit.

Mr Trump said Wednesday he'd be very disappointed in Kim if reports are accurate that North Korea has begun rebuilding a separate missile test site it dismantled last year.

"I would be surprised in a negative way if he did anything that was not per our understanding. But we'll see what happens,"Trump told reporters.

"I would be very disappointed if I saw testing."

Images from Beyond Parallel, part of the Washington-based Center for Strategic and International Studies, showed that North Korea was rebuilding a long-range rocket site at the Sohae launch facility.

The US is aware of the images but hasn't drawn the same conclusions as experts, a senior official at the US State Department said on Friday (March 8). The White House and the Pentagon did not immediately respond to requests for comment.

Earlier this week, the Chosun Ilbo newspaper reported South Korea's National Intelligence Service told lawmakers that it detected signs of North Korea restoring part of the Tongchang-ri missile launch site it tore down in July.

Mr Lewis, told Reuters the activity at the two sites was "probably connected."

Other experts, including Joel Wit at 38 North and Michael Elleman of the International Institute for Strategic Studies considered the conclusion speculative.

"In the past there have been multiple reports about activity at this place that turned out to be false alarms," Wit said, referring to Sanumdong.

"It could either be preparation for an eventual launch or not."

North Korea has frozen nuclear and missile testing since 2017, and Trump has pointed to this as a positive outcome from nearly a year of high-level engagement with North Korea.

Sohae has been used in the past to test missile engines and to launch rockets that US officials say have helped development of North Korea's weapons programs. A senior US State Department official said on Thursday that any launch from there would be "inconsistent" with North Korean commitments.

Kim pledged at a first summit with Trump in Singapore in June that the engine test site and launch platform at Sohae would be dismantled. He repeated the pledge in a summit with the South Korean president in September.

Trump said he thought his and the US relationship with Kim and North Korea was "a very good one." "I think it remains good," he said.

SUMMIT COLLAPSE

Mr Trump has been eager for a big foreign policy win on North Korea which has eluded his predecessors for decades and has repeatedly stressed his good relationship with Kim.

He went as far late last year as saying that they "fell in love," but the bonhomie has failed to bridge the wide gap between the two sides and a second summit between them collapsed last week in Vietnam over differences on US demands for Mr Kim to give up his nuclear weapons and North Korea's demands for sanctions relief.

US National Security Adviser John Bolton and other US officials have sought to play down the developments spotted at Sohae, although Mr Trump on Thursday called recent North Korean activity "disappointing."

The senior State Department official who briefed reporters in Washington on Thursday said he would "not necessarily share the conclusion" of the think tanks that the Sohae site was operational again, but said any use of it would be seen as "backsliding" on commitments to Trump.

Pyongyang has used Sohae to launch satellites into space since 2011, and one such launch in April 2012 killed off an Obama administration deal for a freeze in North Korean nuclear and missile testing in return for food aid.

North Korean state media acknowledged the fruitless Hanoi summit for the first time on Friday, saying people were blaming the US for the lack of an agreement.

"The public at home and abroad that had hoped for success and good results from the second ... summit in Hanoi are feeling regretful, blaming the U.S. for the summit that ended without an agreement," its Rodong Sinmun newspaper said.

The paper directed fiery rhetoric against Japan, accusing it of being "desperate to interrupt" relations between Pyongyang and Washington and "applauding" the breakdown of the summit.

Washington has said it is open to more talks with North Korea, but it has rejected an incremental approach to negotiations sought by Pyongyang and it remains unclear when the two sides might meet again.

US 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 had received "no commitment yet."

The senior State Department official who briefed reporters on Thursday declined to say whether there had been direct contact between the sides since the summit. He said Washington was keen to resume talks as soon as possible, but North Korea's negotiators needed to be given more latitude.

"There will necessarily need to be a period of reflection here. Both sides are going to have to digest the outcome to the summit," said the official, who spoke on condition of anonymity.

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

The official said complete denuclearisation was the condition for North Korea's integration into the global economy, a transformed relationship with the US and a permanent peace regime on the Korean peninsula.

Mr Bolton, who has argued for a tough approach to North Korea, said this week that Mr Trump was open to more talks, but also warned of tougher sanctions if North Korea did not denuclearise.