In this undated image made from video distributed Sept. 6, 2016, by North Korean broadcaster KRT, a missile is launched during a drill at an undisclosed location in North Korea. (AP)

North Korea has taken a key step toward its goal of developing a nuclear-tipped missile capable of reaching the mainland United States, analysts said Friday after Kim Jong Un ordered yet another nuclear test.

The test, which Pyongyang said was a “nuclear warhead explosion,” appeared to be North Korea’s biggest yet.

“It’s a clear indication of progress towards developing a miniaturized nuclear warhead for North Korea’s ballistic missiles,” said Alison Evans, a North Korea analyst at IHS Markit, a consultancy.

“We estimate that North Korea has an inventory of 15 or 20 nuclear weapons and that they could be put on a truck or a short-range missile. But what North Korea is aiming for is to put them on an intercontinental ballistic missile,” she said.

North Korea was officially founded 68 years ago Friday — the day of the nuclear test — with opposition to the United States as its raison d’etre. Its propaganda lauds the protection the Kim family has provided from the “hostile” Americans.

The Washington Post's Anna Fifield reports on North Korea's fifth nuclear test and what it means for the region and one of Kim Jong Un’s few allies, China. (Jason Aldag,Anna Fifield/The Washington Post)

But the reclusive country has dramatically accelerated its nuclear and missile programs since Kim Jong Un became North Korea’s third-generation leader almost five years ago, conducting three of its five nuclear tests in that time.

[ North Korea conducts fifth nuclear test, claims it has made warheads with ‘higher strike power’ ]

Since early 2014, Pyongyang has also noticeably stepped up its missile testing, launching a variety of vehicles, including some long-range missiles. Last month, it successfully launched a ballistic missile from a submarine.

On Monday, North Korea launched three extended-range Scud missiles in quick succession, apparently to try to outsmart U.S. and Japanese missile-defense systems in the region.

Then, on Friday, it said it had “standardized” nuclear warheads so that it could produce “a variety of smaller, lighter and diversified nuclear warheads of higher strike power.”

The test showed that North Korea is “ready to retaliate against the enemies” and has “practical countermeasures to the racket of threat and sanctions” against Pyongyang, the official Korean Central News Agency said.

It is impossible to verify North Korea’s claim to have mastered the technology to fit warheads to missiles, as that proof would come only with a test. And Pyongyang does have a habit of exaggerating its abilities, with its claim to have tested a hydrogen bomb in January immediately dismissed as fanciful.

But Kim’s regime has clearly been working toward being able to deliver a nuclear-tipped missile on target.

In March, state media announced that North Korean scientists had miniaturized a nuclear warhead, and photos were published of Kim examining what was described as a miniaturized weapon — a mirrored device that looked like a disco ball.

While there is still considerable skepticism that North Korea has been able to make such a breakthrough, there is also an increasing assumption among military officials in South Korea and the United States that it’s only a matter of time until North Korea gets there.

[These North Korean missile launches are adding up to something very troubling]

“Twenty years ago, the idea of North Korea being able to deliver a nuclear warhead to the U.S. seemed far-fetched,” said Sharon Squassoni, director of the proliferation prevention program at the Center for Strategic and International Studies. “They’re not there yet, but with each round of tests, they inch a little bit closer.”

But the countries in North Korea’s neighborhood are already at risk, Squassoni said. “This nuclear material could be put on a boat or an airplane or even a wheelbarrow and delivered to North Korea’s neighbors.”

Indeed, the way North Korea described its capabilities — linking them to an artillery unit — suggests that it is focused closer to home, said Joshua Pollack, editor of the Nonproliferation Review.

“They described this as a step that was necessary for them to mass-produce warheads for the theater, underscoring that regional powers ought to be taking this seriously,” he said.

North Korea has been hinting of more provocations to come. In an angry statement released after the U.N. Security Council condemned its submarine-launched ballistic missile test late last month, a spokesman for the Foreign Ministry in Pyongyang warned of “deadly strikes to be made by the enraged people” of North Korea.

“Now that the U.S. posed threats to the dignity and the right to existence of the DPRK, defying its serious warning, it will continue to take a series of eventful action steps as a full-fledged military power,” the spokesman said, using the official abbreviation for North Korea.

While it is easy to dismiss North Korea’s florid rhetoric as exaggeration, analysts carefully parse such statements for clues as to what Pyongyang might do next and have found that they sometimes bear out.

[Everything you need to know about the North Korean nuclear test]

Dealing with North Korea will be a major challenge for the next U.S. administration, regardless of who wins the presidency. The Obama administration has generally followed a policy of “strategic patience,” trying to wait out North Korea, which, under Kim, has shown very little interest in negotiating away its nuclear program.

The international community should try to stymie North Korea’s progress before it reaches its goal, Squassoni said. “It’s still a little way off in the future until that capacity emerges, but we should not wait until this is a real threat before we try to deal with it.”

One immediate effect of North Korea’s latest nuclear test is that it could bolster calls for South Korea to have its own nuclear weapons, said Euan Graham, a security expert at the Lowy Institute for International Policy in Sydney who once served as a British diplomat in Pyongyang.

As North Korea has made advances in its nuclear weapons technology, a small but growing number of prominent politicians and academics have been openly advocating for South Korea to have nuclear weapons, too.

“Some people in South Korea might question if the U.S.’s nuclear deterrence is enough,” Graham said, “and wonder if they should have weapons, too, or if they should be pushing for the U.S. to bring nuclear weapons back to South Korea.”

That idea was gaining traction on social media Friday.

“I strongly support South Korea’s nuke armament,” one commenter said in a forum on the Naver Internet portal, according to the Yonhap News Agency. “As I should know how to protect myself, we should defend our own country. An independent defense is the answer.”

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