North Korea fired hundreds of artillery shells in waters near South Korean border islands on Jan. 5. Last week, it said it no longer regarded the South as inhabited by “fellow countrymen” but as a “hostile state” it would subjugate through a nuclear war. On Friday, it said it had tested an underwater nuclear drone to help repel U.S. Navy fleets.

That new drumbeat of threats, while the United States and its allies have been preoccupied with the wars in Ukraine and the Middle East, has set foreign officials and analysts wondering whether the North’s leader, Kim Jong-un, has moved beyond posturing and is planning to assert more military force.

For decades, a central part of the North Korean playbook has been to stage carefully measured and timed military provocations — some aimed at tightening internal discipline, others at demanding attention from its neighbors and the United States, or all of that at once.

But to several close watchers of North Korea, the latest round of signals from Mr. Kim feels different. Some are taking it as a clue that the North has become disillusioned with seeking diplomatic engagement with the West, and a few are raising the possibility that the country could be planning a sudden assault on South Korea.

Two veteran analysts of North Korea — the former State Department official Robert L. Carlin and the nuclear scientist Siegfried S. Hecker — sounded an alarm this past week in an article for the U.S.-based website 38 North, asserting that Mr. Kim was done with mere threats. “Kim Jong-un has made a strategic decision to go to war,” they wrote.

Analysts broadly agree that North Korea has been shifting its posture in recent years, compelled by an accumulation of both internal problems, including a moribund economy and food and oil shortages, and frustrations in its external diplomacy, like Mr. Kim’s failure to win an end to international sanctions through direct diplomacy with President Donald J. Trump. And most agree that the North’s recent closeness with Russia, including supplying artillery shells and missiles for use in Russia’s war in Ukraine, will be a game-changer in some way.

But there is still stark disagreement over where Mr. Kim’s new tack might be leading.

Many say that Mr. Kim’s ultimate goal remains not a war with South Korea, a treaty ally of the United States, but Washington’s acceptance of his country as a nuclear power by prompting arms-reduction talks.

“The North Koreans won’t start a war unless they decide to become suicidal; they know too well that they cannot win the war,” said Park Won-gon, a North Korea expert at Ewha Womans University in Seoul. “But they would love their enemies to believe that they could, because that could lead to engagement and possible concessions, like the easing of sanctions.”

Analysts in China, North Korea’s most vital ally, were also deeply skeptical that Mr. Kim would go to war unless the North were attacked. Prof. Shi Yinhong, at Renmin University in Beijing, asserted that the North’s leadership, not being irrational, ultimately acted out of self-preservation — and that starting a war would work against that goal.

Others noted that the North could assert itself militarily, including through smaller conventional strikes and bolder weapons testing, without necessarily triggering a deadly response.

“There are many rungs of the escalation ladder that North Korea can climb short of all-out war,” said Victor Cha, a Korea expert at the Washington-based Center for Strategic and International Studies. “Kim is not that confident in his capabilities to deter U.S. reaction if he were to do something rash.”

If Mr. Kim wants to climb that ladder, recent history suggests that this might be the time.

North Korea has liked to unsettle its enemies at their most sensitive political moments, and both the United States and South Korea are holding elections this year. The North launched a long-range rocket in late 2012, between the United States and South Korean presidential elections. It conducted a nuclear test shortly before the inauguration of a South Korean leader in 2013. In 2016, it conducted another nuclear test two months before the American presidential election.

North Korea could also attempt provocations in the coming weeks to try to help liberals who favor inter-Korean negotiations win parliamentary elections in South Korea in April, said the analyst Ko Jae-hong at the Seoul-based Institute for National Security Strategy. Through provocations, North Korea hopes to spread fears among South Korean voters that increasing pressure on the North, as the current administration of President Yoon Suk Yeol has tried to do, might “lead to a nuclear war,” he said.

North Korea “will continue to increase tensions until after the U.S. elections,” said Thomas Schäfer, a former German diplomat who served twice as ambassador to North Korea. But “at the height of tensions, it will finally be willing to re-engage with a Republican administration in the hope to get sanctions relief, some sort of acceptance of their nuclear program, and — as main objective — a reduction or even complete withdrawal of U.S. troops from the Korean Peninsula,” Mr. Schäfer said in a rebuttal to Mr. Carlin’s and Mr. Hecker’s analysis.

Since Mr. Kim came to power in 2011, he has committed to building North Korea’s nuclear capability, using it both as a deterrent and as a negotiating tool to try to win concessions from Washington, like the removal of U.N. sanctions, to achieve economic growth.

He tried it when he met Mr. Trump in 2018 and again in 2019. It failed spectacularly, and Mr. Kim returned home empty-handed and in humiliation.

He then vowed to find a “new way” for his country.

Since then, the North has rejected repeated calls from Washington for talks. It has also rejected South Korea as a dialogue partner, indicating from 2022 that it would use nuclear weapons against South Korea in a war and abandoning its long-held insistence that the weapons would keep the Korean Peninsula peaceful as a deterrent. It has tested more diverse, and harder-to-intercept, means of delivering its nuclear warheads.

There is doubt that the North has yet built a reliable intercontinental ballistic missile that could target the United States. But two of the North’s main enemies, South Korea and Japan, are much closer.

On the diplomatic front, Mr. Kim has taken pains to signal that he no longer views the United States as a critical negotiating partner, instead envisioning a “neo-Cold War” in which the United States is in retreat globally. He has aggressively improved military ties with Russia, and in return has most likely secured Russian promises of food aid and technological help for his weapons programs, officials say.

“I worry that his confidence might lead him to misjudge with a small act, regardless of his intention, escalating to war amid a tense ‘power-for-power’ confrontation with the United States and its allies,” said Koh Yu-hwan, a former head of the Korea Institute for National Unification in Seoul.

Despite its own increasingly aggressive military posture in recent years, China may prove to be a damper on any North Korean military adventurism.

China and North Korea are bound by a treaty signed in 1961 that requires each country to provide military assistance if the other is attacked. But China has little incentive to be drawn into a war in Korea right now.

“A war on the Korean Peninsula would be disastrous for Beijing. An entire half-century of peace in East Asia, a period of unprecedented growth for the P.R.C., would come to a crashing halt,” said John Delury, a professor of Chinese studies at Yonsei University in Seoul, referring to the People’s Republic of China.

The United States has long leaned on Beijing to rein in North Korea. By drawing close to Moscow, Mr. Kim has been putting his own pressure on China’s leader, Xi Jinping.

“It is notable that Kim made his first post-pandemic trip to the Russian Far East, skipping China, and he just sent his foreign minister to Moscow, not Beijing,” Mr. Delury said. By raising tensions, Mr. Kim “can see what Xi is willing to do to placate him,” he added.

David Pierson and Olivia Wang contributed reporting from Hong Kong, and Edward Wong from Washington.