Making their parade debut on launcher trucks with huge wheels were very large missiles encased in tubes or canisters. Analysts said the tubes appeared to have been designed for two other kinds of long-range ballistic missiles. There were multiple examples of each tube; it was impossible to see what was in them, but analysts said it was likely that they contained missiles that were either completed or under development.

Militaries use such canisters to “cold launch” missiles, ejecting them high into the air before their fuel ignites. If North Korea perfected that technology, it would help the nation better protect its mobile missiles from environmental damage while being driven around and from fiery exhaust during launch. The method can also make missiles harder to detect once fired.

“They’re not just showing off missiles that are hard to build,” said Jeffrey Lewis, a North Korea specialist at the Middlebury Institute of International Studies at Monterey, in California. “They’re showing off all the associated technologies you need for credible deployments.”

Kim Dong-yub, a missile expert at the Institute for Far Eastern Studies at Kyungnam University in Seoul, said one kind of tube appeared to be for the KN-14, a modified version of the KN-08 that was first displayed in a parade in 2015, during which the North claimed that its missiles were tipped with nuclear warheads.

The other tube design was new to the analysts. “Given the size, it looks like it contains a new ballistic missile with a range of at least 6,000 kilometers,” or 3,700 miles, making it potentially an intercontinental threat, said Shin In-kyun, a military expert who runs the Korea Defense Network, a civic group specializing in military affairs. “Officials in the region will scramble to figure out whether this is a new solid-fuel, long-range ballistic missile the North was believed to be developing.”