SEOUL — North Korean leader Kim Jong Un said  he no longer felt bound by a self-imposed moratorium on testing nuclear weapons and long-range missiles, and warned the world would soon see a “new strategic weapon” as his country continued to bolster its nuclear deterrent.

In remarks delivered Tuesday at a key meeting of the ruling Workers’ Party and carried by state media Wednesday, Kim complained that the United States had responded to the moratorium by continuing to conduct military drills with South Korea, breaking a promise given by President Trump.

It had also shipped advanced military equipment to South Korea and imposed new sanctions on the North, he said, complaining of a “hostile” policy and “gangster-like acts.”

“He stressed that under such condition, there is no ground for us to get unilaterally bound to the commitment any longer, the commitment to which there is no opposite party, and this is chilling our efforts for worldwide nuclear disarmament and non-proliferation,” the Korean Central News Agency reported.

Kim had previously warned that he would put his country on a “new path” if the United States failed to drop what Pyongyang calls a hostile attitude and make fresh concessions by the end of 2019, threatening to deliver an unwelcome “Christmas gift” to the United States. While Christmas came and went without any missile tests, this week’s statement shows Kim moving in a more aggressive direction.

In his speech Tuesday, he warned that the country would soon unveil a “new strategic weapon,” which experts saw as a sign that he might test a new intercontinental ballistic missile (ICBM).

North Korea has not tested nuclear arms or long-range missiles in more than two years, since declaring its nuclear deterrent to be complete. But as relations with the United States nose-dived last year, it carried out more than a dozen tests of short-range ballistic missiles and rockets.

“North Korea has, in effect, put an ICBM to Donald Trump’s head in order to gain the two concessions it wants most: sanctions relief and some sort of security guarantee,” said Harry Kazianis, a senior director of Korean Studies at the Center for the National Interest. “Kim Jong Un is playing a dangerous game of geopolitical chicken.”

Kazianis predicted any ICBM test would backfire on North Korea, forcing Washington to respond, probably with more sanctions, an increased military presence in East Asia and more “fire and fury”-style threats from Trump’s Twitter account, leading to a dangerous escalation in tension.

Kim also pledged to “put on constant alert the powerful nuclear deterrent capable of containing the nuclear threats from the U.S.” But at the same time, he left open a small window for compromise, by adding that the “scope and depth of bolstering our deterrent” would depend on “the U.S. future attitude.”

Kim’s comments came at a rare four-day meeting of the ruling party’s policymaking committee.

He stressed North Korea’s commitment to develop its economy but said Pyongyang would not succumb to sanctions pressure from the United States.

“It is true that we urgently need external environment favorable for the economic construction but we can never sell our dignity which we have so far defended as valuable as our own life, in hope for brilliant transformation,” Kim was quoted as saying.

Kim said North Korea would not allow the United States to “abuse the DPRK-U.S. dialogue for meeting its sordid aim” and threatened to “shift to a shocking actual action.” DPRK stands for North Korea’s formal name, the Democratic People’s Republic of Korea.

Duyeon Kim, a senior adviser on Northeast Asia at the International Crisis Group, said the speech was measured, calculated and calm, with North Korea continuing with “business as usual” in its efforts to become an economic and nuclear powerhouse through self-reliance. She also noted Kim’s comments about not giving up security for “visible economic results and happiness and comfort.”

“They’re basically saying that nuclear weapons are integral to their economic success, rejecting Washington’s argument or formula that scrapping nuclear weapons guarantees economic prosperity,” she said.

“We can expect Pyongyang to take a harder line this year, but Kim has still left the door open to diplomacy and kept the ball in Washington’s court by saying that any chance for denuclearization is contingent upon U.S. actions and intentions,” she added.

Kim has met Trump three times since June 2018, but nuclear negotiations have failed to yield substantive progress, and the rhetoric between the two sides has become much chillier. Adam Mount, a senior fellow at the Federation of American Scientists, said the United States and South Korea should still stick to the path of dialogue.

“So far, the Trump administration has been ‘fire and fury’ or ‘we fell in love.’ Both exacerbate a bad situation. The imperative is to find a responsible option in the vast space between,” he said.

“The United States still has considerable leverage to shape North Korea’s arsenal, but it will require a far more patient and flexible approach than any president has been willing to demonstrate,” he said.

Kim’s speech to the party meeting replaced a televised News Year’s address that he had delivered in previous years, and was heavily covered by state media. Although North Korean leaders have traditionally delivered a New Year’s message, it has sometimes taken the form of written texts, and sometimes audio and/or televised speeches.

Trump, speaking to reporters as he entered a New Year’s Eve party at his personal resort, Mar-a-Lago, declined to comment specifically on North Korea’s latest statement. The president stressed that he believed Kim was a “man of his word,” who had signed an agreement in Singapore talking about denuclearization.

“We’ll see,” Trump said. “I have a very good relationship with Kim Jong Un.”

“I know he’s sending out certain messages about Christmas presents and I hope his Christmas present is a beautiful vase . . . as opposed to something else,” Trump said.

North Korea says the United States consistently misrepresents what was agreed in Singapore, stressing that Kim and Trump agreed to work toward the complete denuclearization of the entire Korean Peninsula, not the unilateral denuclearization of the North.

South Korea’s Unification Ministry welcomed the fact that Kim had not announced an end to dialogue with the United States, as some had feared it would, but warned that a strategic weapons test “will not help with nuclear negotiations and efforts to settle peace on the Korean Peninsula.”

It added that South Korea and the United States have been “virtually holding back from large-scale joint exercises” during the dialogue process with the North.

Denyer reported from Tokyo.