TOKYO — North Korea appears to be taking steps toward a new test of a powerful submarine-launched missile, U.S. weapons experts said, as it steadily dials up the pressure on President-elect Joe Biden.

Last week, a beaming Kim Jong Un presided over another demonstration of his country’s military might in a nighttime parade in Pyongyang, kicked off with a fireworks display. Now, it appears he might be planning a very different fireworks display to greet the incoming U.S. president.

On show at the parade was a new ballistic missile designed to be launched from a submarine, with state media over-enthusiastically describing it as “the world’s most powerful weapon.” Satellite evidence has emerged of work at a naval base in the port city of Nampo on the country’s west coast that suggests preparations could be underway for a test launch of a similar missile.

North Korea held a military parade on Jan. 14 and included the showcasing of what appeared to be a new submarine-launched ballistic missile. (Reuters)

While the evidence is not conclusive, it does fit a pattern of steadily more aggressive posturing from North Korea’s leader.

Commercial satellite photos taken on Dec. 31 by the firm Maxar depicted work underway on a submersible barge of the type used in the past for tests of submarine-launched missiles, according to an analysis of the images by Jeffrey Lewis and David Schmerler, weapons experts at the James Martin Center for Nonproliferation Studies in Monterey, Calif.

Since November, the long-dormant barge has been hauled from its usual moorings to a nearby dry dock, an unusual move that suggests that North Korean officials are “preparing to use the barge for a launch” in the near future, Lewis and Schmerler wrote in their analysis, which was published Monday. Copies of the images and analysis were provided to The Washington Post.

In a speech to a ruling party congress this month, Kim said he would “tirelessly strengthen” North Korea’s military, expand its nuclear arsenal and develop new nuclear-tipped missiles capable of reaching Washington, pointedly calling the United States his country’s “biggest enemy.”

The submarine-launched ballistic missile unveiled last week could have a range of about 1,900 miles, according to Michael Elleman, director of nonproliferation and nuclear policy at the International Institute for Strategic Studies, writing in a piece for the 38 North website. That means it would be capable of reaching Guam from the Sea of Japan, also known as the East Sea.

Any test of a missile of that range would be a significant headache for the Biden administration, violating United Nations Security Council resolutions although not breaking North Korea’s self-imposed moratorium on inter-continental ballistic missile (ICBM) and nuclear weapons tests.

While the activity around Nampo is suggestive of a pending test, Lewis and Schmerler said it was not possible to predict when a launch would occur.

Duyeon Kim at the Center for a New American Security said North Korea always has a military imperative to test its weapons and perfect its technology, but she predicted the timing of any test would be politically driven — perhaps in reaction to joint U.S.-South Korea military exercises or American criticism of North Korea’s human rights record.

But there are already signs North Korea is far from happy, said Andrei Lankov, a professor at Kookin University in Seoul. Pyongyang fears that Biden is not going to give the regime what it wants and is not particularly interested in talks, he said.

“When the North Koreans are not happy about the situation, what do they do?” he asked. “They have done the same thing for decades. They manufacture a small, nice, manageable crisis.”

In the campaign, Biden called Kim a “thug,” and Lankov said the new U.S. president, with a lot on his plate, may return to the “strategic patience” doctrine adopted by the Obama administration, albeit without success.

“That is essentially the assumption that one day, sooner or later, North Korea will crumble under the pressure of its economic problems and will come wagging its tail, asking for concessions,” Lankov said. “Basically, Kim Jong Un is sending a message: ‘No chance, Mr. Biden, not going to happen. Instead of wagging our tails, we are snarling our teeth and biting, and we are not even going to guarantee the security or survival of your people.’ ”

Lankov predicts a gradual, systematic intensification of pressure on the United States, moving from parades and verbal threats toward missile tests.

But Vipin Narang, an associate professor of political science at MIT, takes a different view. He would not rule out a provocative test but said it is equally possible that Kim, already struggling to keep the coronavirus at bay, maintain food production and prop up the economy, could bide his time.

“Time is on Kim’s side, so why rock the boat, especially given potentially serious domestic problems?” he asked. “Kim doesn’t need to be the new kid screaming for attention, especially if he can quietly improve and expand his force, as he’s doing.”

Even when Kim was sending flattering letters to President Trump extolling their friendship, U.S. and South Korean intelligence agencies assessed that North Korea never stopped working on new missiles or amassing fissile material for nuclear bombs.

Then, as the dialogue with Washington crumbled, Kim announced at the beginning of last year that he no longer felt bound by a self-imposed moratorium on ICBM or nuclear tests.

A year later, though, North Korea’s leader has yet to follow through on that threat.

Experts say it is a line that China, never more important in its economic support for North Korea, will not be keen to see crossed. Still, the signs are ominous.

Kim promised this month to develop solid-fuel ICBMs that can be launched from land and sea, and Lewis and Schmerler said there is a variety of evidence suggesting this process is underway — despite indications that North Korea’s military development has been slowed by the pandemic and its economic woes, experts say. The unveiling of a massive new solid-fuel ICBM during a military parade in October suggests that the missile program has continued to advance.

“As Trump leaves office, North Korea has been taking steps to abandon the moratorium that Kim renounced last year,” Lewis and Schmerler wrote. “The Biden administration is inheriting a North Korea that is moving toward resuming flight-tests of intermediate- and intercontinental-range missiles.”

North Korea conducted a successful test launch of a solid-fueled submarine-launched missile — dubbed the Pukguksong-3 — off North Korea’s eastern coast in October 2019.

Solid-fuel missiles can be launched quickly and have greater survivability compared with the liquid-fueled missiles that make up the bulk of Kim’s arsenal, but, stored in silos or carried on submarines, they can be more easily targeted by preemptive military strikes.

Whatever Kim decides to do, he is sending Biden a clear message, experts say. He is never going to abandon his nuclear weapons, and if the United States wants to talk about some kind of freeze or reduction in Pyongyang’s arsenal, he will demand a very high price.

“Americans still live in a dream world, a sort of alternative universe where North Korea is run by people who are naive enough to consider denuclearization,” Lankov said.

“They have seen Libya, they have seen Afghanistan, they have seen Iraq, they have seen Ukraine, Crimea. North Korean leaders have always believed nuclear arms are the only guarantee of their political and perhaps physical survival. They have made clear many times their goal is some kind of deal with the United States which will include their explicit or implicit acceptance as a nuclear power.”

Warrick reported from Washington.