All of the capsules will be closed down in a few years, as the military’s new ICBM, the Sentinel, comes online.

But even a solid-fuel ICBM, mounted on a giant transporter-erector-launch vehicle, must be rolled out of cover – a bunker, tunnel, warehouse or even from under a bridge – before being elevated and fired.

“There’s nothing new here technically as far as I can tell at this early stage, but they’re certainly growing increasingly confident in their new solid propellant ICBM.”

If Monday's launch is confirmed to be an ICBM, it would be the North's fifth launch of such weapons this year- the highest ever for a single year.

“It’s been a long time since we did an ICBM,” Kendall said in November at a Center for New American Security event in Washington.