North Korea says it performed a nuclear test at plant that was supposed to be dismantled

North Korea said Sunday that it successfully conducted a “very important test” at a long-range rocket launch site, which had previously been partially dismantled as part of nuclear talks with the United States.

The brief statement, which provided few details, came a day after North Korea’s ambassador to the U.N. said denuclearization was off the negotiating table, accusing the Trump administration of using the process for political gains ahead of the 2020 U.S. election.

Pyongyang has given Washington an end-of-year deadline to offer concessions to restart talks, which stalled after a failed summit between President Donald Trump and North Korean leader Kim Jong Un in February in Vietnam.

The communist state has already resumed short-range weapons tests and issued a series of warnings that experts say could herald a return to the cycle of missile launches and threats that pushed the divided peninsula to the brink of war in 2017.

Sunday’s announcement referred to the Sohae Satellite Launching Ground, which experts say has been used to develop technology for the North’s intercontinental ballistic missile program.

Commercial satellite imagery showed key facilities being razed at the site in an apparent goodwill gesture shortly after the first summit between Kim and Trump in Singapore, where they agreed to a vague promise to “denuclearize the Korean Peninsula.”

But CNN reported that images taken Thursday by Planet Labs showed new activity and the presence of a large shipping container, raising speculation that a test would occur.

“A very important test took place at the Sohae Satellite Launching Ground” on Saturday,” the state-run Korean Central News Agency reported, adding that it had been “successful.”

“The results of the recent important test will have an important effect on changing the strategic position of [North Korea] once again in the near future,” KCNA said.

It didn’t say what was tested, but experts said it was likely a rocket engine. The South Korean military said it had not detected anything being fired from the northwestern complex.

North Korea insists the facility is part of a peaceful space program.

The developments raised concern that the diplomatic process was unraveling after months of reported progress that included summits and a self-imposed North Korean moratorium on long-range missile and nuclear tests.

Trump, who last year said he and Kim “fell in love,” insisted the relationship remains good.

“I have a very good relationship with Kim Jong Un. I think we both want to keep it that way,” he said Saturday at the White House. “He knows I have an election coming up. I don’t think he wants to interfere with that, but we’ll have to see.”

“The relationship is very good, but you know there is a certain hostility. There’s no question about it,” he added. “I don’t know that his relationship with South Korea is very good, but we’re going to find out.”

The remarks came a day after Trump spoke on the phone with South Korean President Moon Jae-in to discuss ways to maintain diplomacy with the North, according to Moon’s office.

Last week, Trump warned the U.S. may have to use military force against the North if necessary, prompting an angry reaction from the communist state.

The two sides also hinted the name-calling from 2017 may resume, with Trump referring to Kim as “rocket man” and the North saying his remarks may be a sign of “the relapse of the dotage of a dotard.”

North Korea’s ambassador to the United Nations, Kim Song, then said denuclearization was off the table and called the dialogue sought by Washington a “time-saving trick” to promote its political agenda ahead of Trump’s reelection bid.

“We do not need to have lengthy talks with the U.S. now,” he said.

The North Korean moves are part of its negotiating playbook, said Jean Lee of the Washington, D.C.-based Wilson Center.

“As contradictory as it may seem, these threats & low-level provocations are #NorthKorea’s way to try to compel Trump to make a bold move, quickly,” she wrote on Twitter.

But Kim Jong Un is also hedging his bets in case that doesn’t happen by “setting the stage to justify future provocations designed to bolster support at home,” she said.