SEOUL, South Korea >> North Korea’s leader, Kim Jong Un, vowed to expand his nuclear arsenal “at the fastest possible speed​” and threatened to use it, as his government displayed a large array of missiles and other weapons, including its newest intercontinental ballistic missile, during a nighttime military parade Monday, the North’s state media said.

With his defiant tone, Kim ​appeared to raise the stakes in ​the stalled international efforts ​to curtail his nuclear weapons ambition. North Korea’s growing nuclear and missile threat ​will probably be one of the most pressing diplomatic issues discussed during an expected meeting next month between President Joe Biden and South Korea’s president​-elect​,​ Yoon Suk-yeol.

Yoon, who takes office May 10, has said he will align South Korea’s policy on North Korea closer to that of Washington’s by reinvigorating sanctions enforcement on the North. He is expected to meet with Biden in Seoul after his inauguration and before Biden travels on to Japan to attend a regional security forum.

“The nuclear forces, the symbol of our national strength and the core of our military power, should be strengthened in terms of both quality and scale,” Kim said in a speech he delivered during a large parade in Pyongyang, the capital, on Monday night to mark an important military anniversary, according to the North’s official Korean Central News Agency.

Kim said that although North Korea has built its nuclear weapons as a deterrent, “our nukes can never be confined to the single mission of war deterrent.”

“If any forces try to violate the fundamental interests of our state, our nuclear forces will have to decisively accomplish its unexpected second mission,” he said.

In recent weeks, North Korea has raised the possibility of using nuclear weapons should war break out on the Korean Peninsula. During his election campaign, Yoon said South Korea would consider “preemptive ​strikes” against the North’s nuclear forces if the South were under nuclear threat.

North Korea has since warned that it could use nuclear weapons ​during a conflict. This month, North Korea reported a successful test of a new missile that it said would significantly enhance its short-range tactical nuclear capabilities​. Such capabilities — along with nuclear-armed Russia’s invasion of the non-nuclear state Ukraine — have increased South Korean fears over Kim’s nuclear program.

Kim has staged a dozen military parades since he took power a decade ago, using the events to boost the morale of his people, long suffering under international sanctions, and to display his nuclear arsenal, which is his single biggest achievement as leader. The parades are monitored closely by outside analysts and officials because Kim has often used them to ​show off his new ​weapons.

On display during the parade Monday night ​was the Hwasong-17​, the North’s newest and largest ICBM​, according to photos released through North Korean news media​. ​Kim appeared in his white military marshal’s uniform bedecked with golden buttons and epaulets.

“It’s unusual for Kim Jong Un to deliver a speech during a parade in his marshal’s uniform,” said Cheong Seong-chang, director of the Center for North Korean Studies at the Sejong Institute, a research think tank in South Korea. “This signals an extremely hard-line stance he will likely adopt toward the incoming South Korean government of Yoon Suk-yeol, who has voiced a hawkish stance toward the North.”​

During his speech, Kim exhorted his people to brace themselves for a confrontation with their external enemies “for a long period of time.” The parade also featured military jets flying in formation, neat columns of goose-stepping or horse-riding soldiers, as well as a host of ​new ​weapons North Korea has been developing or testing in recent years, including submarine-launched ballistic missiles​ and hypersonic missiles.

North Korea has conducted a spate of missile tests in recent months, including an ICBM test on March 24. ​The country claimed to have launched its Hwasong-17 in the March test, but South Korean officials have ​since ​suspected that ​the North actually launched its older Hwasong-15 because ​of technical glitches in the ​Hwasong-17.​

Seoul and Washington have hoped to bring Kim back to the negotiating table, but the military parade was a strong indication that diplomacy will not happen quickly, analysts said.

In 2017, North Korea detonated what it called a hydrogen bomb​ in an underground nuclear test and ​tested three ICBMs​, including the Hwasong-15​. Those tests led to harsher sanctions from the United Nations. ​ Kim ​declared a moratorium on ​all ​ICBM ​and nuclear tests before ​embarking on summit meetings with President Donald Trump in 2018.​ Through his negotiations with ​ Trump, Kim had hoped to lift the sanctions in exchange for a partial dismantling of his nuclear program.

But ​his meetings with Trump ended ​in 2019 ​without an agreement on when to lift the sanctions or how to roll back the North’s nuclear and missile programs. Kim has since apologized to his people for the economic woes caused by the sanctions and the pandemic. ​But he has also ​escalated his nuclear and missile programs.

With the ​Hwasong test last month, North Korea lifted ​the moratorium on ICBM tests. This month, images taken by commercial satellites indicated that North Korea might be reconstructing its underground nuclear test site​, which the North had partly destroyed in 2018 before Kim’s first summit with Trump. The activities there have raised fears that​ the North might be preparing to resume nuclear tests as well.

North Korea’s recent missile tests and other weapons-related activities have been part of an effort by Kim to advance his nuclear capabilities and to pressure Washington to return to the negotiating table with sanctions relief and other concessions, analysts say. The war in Ukraine has also created a favorable environment for Kim to push forward the North’s weapons programs, as Russia and China were likely to block any U.S. attempt to impose fresh sanctions at the U.N. Security Council.

This article originally appeared in The New York Times.