SEOUL, South Korea — North Korea said Sunday that it successfully conducted a “very important test” at a long-range rocket launch site, prompting President Donald Trump to warn that Kim Jong Un could lose “everything” if he acts aggressively.

The statements were the latest sign that hopes for diplomacy are unraveling ahead of a year-end deadline set by North Korea for Washington to offer concessions to restart stalled nuclear talks.

They capped a week of warnings as the communist state suggests it is increasingly impatient over the diplomatic deadlock and might be leaning toward the “new way” mentioned by Kim earlier this year.

On Tuesday, a North Korean diplomat said it is “entirely” up to the U.S. what “Christmas gift” it wants to get as the year draws to a close, prompting speculation North Korea might be preparing for a long-range-missile test.

President Donald Trump, who is eager for foreign policy success in North Korea and consistently has maintained his friendship with Kim, adopted a more threatening tone on Sunday.

“Kim Jong Un is too smart and has far too much to lose, everything actually, if he acts in a hostile way,” Trump wrote on Twitter after the North Korean test was announced.

“He does not want to voice his special relationship with the President of the United States or interfere with the U.S. Presidential Election in November,” he added.

The renewed saber rattling has raised concern that North Korea might lift its self-imposed moratorium on long-range-missile and nuclear-weapon tests, leading to new tensions in 2020.

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

“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,” according to the brief statement attributed to an unnamed spokesman for the North’s Academy of National Defense Science.

KCNA didn’t provide more details, but experts said it probably was a rocket engine. The South Korean military said nothing was fired from the complex, which sits near the North’s border with China.

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

But CNN reported that images taken Thursday by Planet Labs showed new activity and the presence of a large shipping container at the site.

Several U.S. surveillance aircraft also reportedly have flown around the peninsula to monitor for possible North Korean missile activity in recent days.

The adversaries, who remain technically at war since their 1950-53 conflict ended in an armistice instead of a peace treaty, have gone from the brink of another war in 2017 to a series of summits and high-level meetings that boosted hopes for peace in 2018.

Talks stalemated this year after a second summit between Kim and Trump collapsed without agreement in February in Vietnam, and working-level talks failed in October in Sweden.

Pyongyang has demanded security guarantees and extensive relief from punishing economic sanctions aimed at its nuclear program.

But Washington insists it will maintain pressure on the communist state until it takes more significant steps toward dismantlement.

Trump spoke on the phone with South Korean President Moon Jae-in on Friday to discuss ways to maintain diplomacy with the North, according to Moon’s office.

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

The president, who last year said he and Kim “fell in love,” also brought up his reelection bid on Saturday, suggesting concern about the impact of a return to hostilities on public opinion.

“He knows I have an election coming up. I don’t think he wants to interfere with that, but we’ll have to see,” he told reporters at the White House.

The two sides also hinted the name-calling from 2017 might 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 domestic political agenda. “We do not need to have lengthy talks with the U.S. now,” he said Saturday in the clearest indication of the widening gap between the two sides.

Kim Jong Un, meanwhile, is due to convene the ruling party’s central committee later this month, which usually signals a major policy shift.

“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,” Jean Lee of the Washington, D.C.-based Wilson Center wrote on Twitter.

But Kim also is 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. Twitter: @kimgamel

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