North Korea boasted its progress on a new and dangerous solid-fueled missile at a military parade. The country also showed off at least 11 Hwasong-17 ICBMs — Pyongyang's biggest missile yet.If they work properly, these long-range missiles could potentially challenge US defense systems.North Korea unveiled a new design this week for what could be its most dangerous intercontinental ballistic missile yet, as well as enough ICBMs to potentially challenge US defense systems. State media photos of a Wednesday night parade celebrating the 75th anniversary of the founding of the North Korean army showed what looked like a new solid-fueled ICBM, a long-range missile that can deliver nuclear warheads to targets thousands of miles away.The apparent launcher may be functional, but it's more likely a mock-up with an empty canister. Still, experts told Insider its appearance is telling about North Korea's ambitions.Solid-fueled missiles are more dangerous than liquid-propellant systems, which is what North Korea's other ICBMs are, because they can be fueled in advance and launched with little to no warning. Fueling missiles with a liquid propellant can only be done safely just prior to launch, is a time-consuming process, and involves a massive logistical effort that makes launch preparations more visible and leaves them vulnerable to strikes. 

In recent years, North Korea has indicated that its missile program is pivoting toward the use of solid fuel, Ian Williams, deputy director of the Missile Defense Project at the CSIS, told Insider. Examples of this include short-range ballistic missile developments, as well as medium-range missiles like the Pukguksong-2.

Despite international pressure to halt its weapons programs, the country is showing "a lot greater comfort using solid-fuel missiles, and I think it's just a matter of time before they scale this stuff up," Williams said. "We're seeing that now."

what's inside. China, for instance, rarely shows what its missiles look like.

Solid-fueled missiles are sensitive to temperature changes and are usually placed in canisters or silos so their temperatures can be regulated. North Korea has displayed large canisters before, but the ones displayed on Wednesday appear to be more legitimate than those in the past, Williams said. 

"Whether there's a missile inside the canister yet or not, it's hard to say," he said. "But I definitely think that we're seeing the beginnings of what will likely be flight tests of a solid-fuel ICBM."

'It certainly is a wake-up call'

North Korea on Wednesday also showed off a series of Hwasong-17 ICBMs, according to state media images. First unveiled in October 2020, the Hwasong-17 is North Korea's biggest missile, is fired from a transporter erector launcher, and can, assuming it works as intended, strike targets an estimated 9,000 miles away.