WASHINGTON — Kim Jong-un is headed to the moon.
That, at least, is one of the official North Korean explanations for the testing last week of a rocket engine that, if as powerful as the North claims, would rival the commercial rockets that Jeff Bezos and Elon Musk, of Amazon and Tesla, now use in their aerospace companies to fire payloads into space.
Inside the United States’ intelligence agencies, though, there is considerable skepticism that North Korea is truly eager to plant a flag on the lunar landscape. The agencies are exploring another explanation: that Mr. Kim, the North Korean leader, is racing ahead, as the United States is distracted by a bruising presidential election, to develop a way for his growing arsenal of nuclear weapons to reach New York and Washington.
The North may not be working alone. An intelligence finding that the United States quietly made public in January suggests that the development of the North’s big engine, which it claims produces 80 tons of thrust, may be part of a joint partnership with Iran. A Treasury Department announcement of sanctions against Iranian officials and engineers named two who had “traveled to North Korea to work on an 80-ton rocket booster being developed by the North Korean government.”
The Obama administration has responded to North Korea’s nuclear and missile tests with gradually escalating sanctions, mostly through the United Nations. But on Monday it went a step farther, announcing criminal charges and Treasury Department sanctions against four Chinese individuals and a company that it said engaged in money laundering to help the North’s programs for weapons of mass destruction.
The sanctions were against the Dandong Hongxiang Industrial Development Company and its primary owner, Ma Xiaohong, who lives near the North Korean border.
Few threats as urgent as the dramatic escalation of North Korea’s nuclear and missile programs are likely to confront Hillary Clinton or Donald J. Trump as president. An engine that delivers 80 tons of thrust would have about three times the power of an advanced North Korean rocket shown in a ground test in April, though it is not possible to verify the North’s claims. By most unclassified estimates, it will take North Korea perhaps five years to marry its missile advances with a weapon small enough and strong enough to survive the stresses of re-entering the atmosphere atop an intercontinental ballistic missile.
So far, Mr. Kim’s engineers have never executed a military test flight that could reach beyond the middle of the Pacific, though in a statement on Friday, the North threatened to attack Guam, home of the American B-1 bombers that conducted simulated runs last week over the Korean Peninsula.
The potential links to Iran complicate the issue. Iran has ignored a United Nations Security Council resolution, passed in conjunction with last year’s agreement freezing its nuclear program, to refrain from tests of nuclear-capable missiles for eight years.
The Obama administration has not sought sanctions, knowing they would be vetoed by Russia and China, nor has it said much in public about the details of the cooperation on the new rocket engine. There is a long history of sharing missile technology, but no persuasive evidence exists that the Iranians have been involved in the North’s nuclear weapons tests.
The moonshot talk may be aspirational, but it is not lunacy. Rocket experts say four of the new North Korean engines, clustered at the base of a space vehicle, would be powerful enough to hurl a no-frills payload to the moon. But the North would have to master many other technologies before even an unmanned vehicle could be landed there.
In an interview last month with The Associated Press, the director of the scientific research department of North Korea’s National Aerospace Development Administration, Hyon Kwang Il, said a moonshot was the nation’s goal.
“Even though the U.S. and its allies try to block our space development, our aerospace scientists will conquer space and definitely plant the flag of the D.P.R.K. on the moon,” he said, using the abbreviation for the Democratic People’s Republic of Korea.
Whatever the goal, the most important aspect of the new North Korean engine is that its design appears to be indigenous, rather than a knockoff of decades-old Soviet missiles. That suggests a growing domestic ability, which may explain the appeal to Iran, which intelligence officials speculate may be helping to fund the effort.
“It’s like nothing we’ve seen before,” John Schilling, an expert on North Korea’s missile program at 38 North, a blog and think tank of the Johns Hopkins University School of Advanced International Studies, said of the powerful new engine. “It’s somewhat frightening that they have this capability, but somewhat encouraging that they want to use it for space launching.”
History shows that any strides in rocketry, no matter what the claimed purpose, can aid both civil and military programs. “That’s what the United States did,” said David Rothkopf, who has written two histories of the National Security Council. “It’s what the Russians did. It’s what the Chinese did. Why not the North Koreans?”
American officials would not publicly say that the program referred to in the Treasury sanctions was the same one that resulted in last week’s test. But there was no other logical conclusion.
The announcement identified “Iranian missile technicians” from companies working for Iran’s Ministry of Defense for Armed Forces Logistics. It said that two of them, Seyed Mirahmad Nooshin and Sayyed Medhi Farahi, “have been critical to the development of the 80-ton rocket booster, and both traveled to Pyongyang during contract negotiations.”
Dr. Schilling said the big new engine seemed more suited to launching satellites and space probes than warheads. The North Korean military is known to prefer missiles small enough to transport on trucks, haul on back roads and hide in tunnels.
But the North is also highly aware that its launching failures in past years have become the stuff of ridicule on the internet, making it easy to dismiss the program. It seems to be looking for something that would create at least the impression that it will not take long for it to fly to the moon or strike any part of the United States.
“You cluster four of them together, and that’s a very healthy ICBM,” Jeffrey Lewis, a North Korea specialist at the Middlebury Institute of International Studies in Monterey, Calif., said of the new engine.
Of course, moving from a static engine test to a cross-Pacific flight test would take considerable time, and the rocket would be a giant sitting duck for American targeting on the launchpad. One possibility is that the North is trying to replicate elements of the American “triad” — the creation of a nuclear arsenal that can be delivered by aircraft, from ground-based silos and from submarines.
The North Koreans may be thinking, “Why not have everything?” Dr. Lewis said. David C. Wright, a senior scientist at the Union of Concerned Scientists, a Cambridge, Mass., group that monitors proliferation, also argued that North Korea’s advance could well end up powering ICBMs from deep silos.
He noted that the high power of the new North Korean engine was similar to one that Chinese scientists developed to power that nation’s first long-range missile. Dr. Wright, in a blog post on the North Korean advance, noted that the Chinese rocket, known as the DF-5 (for Dong Feng, or East Wind), “could carry a nuclear warhead to anywhere in the United States.”
“Who knows what North Korea might want to do?” Dr. Wright said. “At this point, I don’t think we can take an ICBM off the table.”