Kim Jong Un and Donald Trump
Kim Jong Un and Donald TrumpReuters

US President Donald Trump warned on Sunday that North Korean leader Kim Jong Un had "everything" to lose through hostility towards the United States, AFP reports.

"Kim Jong Un is too smart and has far too much to lose, everything actually, if he acts in a hostile way," Trump tweeted in response to North Korea’s announcement of a major new weapons test at its Sohae space launch center.

The announcement of Saturday's test came just hours after Trump said he would be "surprised" by any hostile action from the North, emphasizing his "very good relationship" with Kim.

The test also took place after North Korea’s ambassador to the United Nations said that denuclearization is off the negotiating table with the United States.

The ambassador, Kim Song, said that the “sustained and substantial dialogue” sought by the United States was a “time-saving trick” to suit its domestic political agenda, a reference to Trump’s 2020 reelection bid.

Trump and Kim engaged in months of mutual insults and threats of devastation in 2017, sending tensions soaring before a diplomatic rapprochement the following year.

The pair have met three times since June 2018, most recently in Vietnam in February, but with little progress towards denuclearization. Pyongyang has set Washington a December 31 deadline to make new concessions to kickstart stalled talks.

Since that June meeting, North Korea has conducted several tests of ballistic missiles.

Trump has said he's "not happy" about North Korea's persistent testing of short-range missiles but denied the launches violate any agreement.

"North Korea, under the leadership of Kim Jong Un, has tremendous economic potential, but it must denuclearize as promised," Trump tweeted on Sunday. "NATO, China, Russia, Japan, and the entire world is unified on this issue!"

Writing that Kim had "signed a strong Denuclearization Agreement" at their June 2018 summit in Singapore," Trump warned, "He does not want to void his special relationship with the President of the United States or interfere with the U.S. Presidential Election in November."