After two months of relative quiet on the missile launch front, North Korea Tuesday tested an intercontinental ballistic missile that, early estimates show, has a range that could hit anywhere in the continental US. But pay close attention to the caveats.

The test came in the dead of night, a little after 3 am local time, with the missile eventually landing in the Sea of Japan about 600 miles away from the launch site. It took nearly an hour to get there, reaching an altitude of about 4,500 miles.

While North Korea had already tested its first ICBM in July, the latest test flew significantly higher and longer. Analysts gauged this summer’s Hwasong-14 missile as having a range of around 4,000 miles—far enough to reach much of Alaska—but Tuesday’s launch quite literally goes much farther.

“If these numbers are correct, then if flown on a standard trajectory rather than this lofted trajectory, this missile would have a range of more than 13,000 km (8,100 miles),” wrote physicist David Wright, co-director of the Union of Concerned Scientists Global Security Program. “Such a missile would have more than enough range to reach Washington, DC, and in fact any part of the continental United States.”

North Korea earlier this year appeared to have gained the ability to miniaturize a nuke, a step that, added to ICBM capabilities, makes for a combustible combination. While several other technological pieces still need to fall into place, with Tuesday’s launch, the Hermit Kingdom's military has cleared yet another hurdle in the path of its offensive ambitions.

The progress did not go unnoticed by the administration. President Donald Trump said following the test that the US “will take care of it,” though did not provide any specifics as to what that might entail. Defense Secretary James Mattis offered a little more depth, noting that the launch “went higher, frankly, than any previous shot they've taken.”

“The bottom line is it is a continued effort to build a ballistic missile threat that endangers world peace, regional peace, and certainly the United States,” Mattis added.

Barriers to Entry

But while North Korea’s ICBM progress rightly rings plenty of alarms, in practice it looks less like a significant technological advancement and more like an incremental improvement.

“It probably was very similar to the missile that they launched twice in July, the Hwasong-14,” Wright tells WIRED. “At the time, in looking at the second stage, we realized that there were some obvious things they could do to increase the capabilities of the second stage, and my guess is that’s what they did this time.”

'President Trump may feel he’s got to do something. Whatever that might be could be provocative.' Philip Coyle, Center for Arms Control and Non-Proliferation

A more significant leap forward would be to increase the size and capability of the engine in the rocket’s second stage—an advance that seemed conspicuously absent in Tuesday’s test. “It appears they don’t have an engine like that to use, or they would have used it,” Wright says. “It’s not clear whether they have the capability to either build that or design that in the near term.”

What North Korea can and cannot do technologically remains shrouded in some mystery; there’s always a chance that it simply chose not to show its hand for whatever reason. But even so, there are further important differences between a test missile that could potentially hit the US and actually doing so.

Take the missile’s payload, the weight of which would dramatically affect just how far it could fly.

“I think that their payload is probably quite small, maybe just some diagnostics instruments to help them know what happened,” says Philip Coyle, senior fellow at the Center for Arms Control and Non-Proliferation and former head of the Pentagon’s test and evaluation office, about Tuesday’s launch. “But a real nuclear weapon, especially one that North Korea might have, could be big and heavy.”

That “big and heavy” doesn't travel as far on the same missile as “quite small” is not the stuff of advanced degrees. While the exact size of North Korea’s potential nuclear payload is unknown, Wright suggests that adding it to a missile like North Korea just tested could shave its range by about a third.