TOKYO - North Korea has unveiled what it said was a domestically designed engine for an intercontinental ballistic missile capable of reaching the United States, the latest in a steady drumbeat of threats coming from Kim Jong Un's regime.
Saturday's announcement, through the official Korean Central News Agency, could not be immediately verified. But analysts said Pyongyang's constant boasts of military advances have sent a clear message to the United States.
"With all the missiles they're building, the ranges are getting longer and they're going to be able to throw more stuff further," said Jeffrey Lewis, director of the East Asia program at the James Martin Center for Nonproliferation Studies in Monterey, Calif.
"It seems pretty clear that they're sick of us making fun of them, and they're going to shove it down our throats," Lewis said.
North Korea recently unveiled a KN-08 road-mobile intercontinental ballistic missile, also known as a Rodong-C, but with engines that did not look like those that had powered other recent launches. This left nuclear scientists scratching their heads.
On Saturday, KCNA said that North Korea had successfully tested, under Kim's supervision, a new "indigenously designed" engine at the Sohae missile launch site near the country's west coast.
"Dear Comrade, Kim Jong Un said now we can mount an ever more powerful nuclear warhead on a new intercontinental ballistic rocket and put the den of evil in the United States and all over the world within our strike range," the news agency said.
Previous estimates of North Korea's firepower had it just able to reach the continental United States, but if it had successfully manufactured an 80-ton booster - as the Treasury Department recently claimed in sanctions against Pyongyang - it would put the U.S. mainland within relatively easy reach, analysts said.
Since North Korea conducted its fifth nuclear test in January, Kim's regime has crowed about a whole range of technical leaps and bounds, from road-mobile multiple rocket launchers and solid-fuel rocket engines to being able to make a nuclear warhead small enough to attach to a missile.
These advances have been accompanied by a series of threats to blow up New York City, the White House and South Korea's presidential Blue House.
Although North Korea has fired a range of projectiles, it has not demonstrated an ability to successfully fire a nuclear-tipped missile and hit a target. That would almost certainly be suicide, given the retaliation from the United States and South Korea that it would provoke.
But an increasing number of military top brass and scientists say that if North Korea doesn't have this capability yet, it's just a matter of time until it does.
South Korean government officials said this week that they thought North Korea had now mastered this technology, while Gen. Curtis M. Scaparrotti, commander of U.S. Forces Korea, and Adm. William Gortney, head of the U.S. Northern Command, have both said the same.
"I assess that they have the ability to put an ICBM in space and reach the continental United States and Canada," Gortney said at a Senate Armed Services Committee hearing last month.
North Korea's boasts come at a sensitive time on the peninsula. The United States and South Korea are conducting joint military drills - which Pyongyang views as a pretext for an invasion - through the end of this month, while North Korea is preparing for its first Workers' Party Congress in 36 years.
The regime has been laying the groundwork for next month's meeting, where Kim is expected to try to bolster his legitimacy as the young, third-generation leader of North Korea. Being able to crow about a strong nuclear deterrent would be a good way to do that, analysts say.