North Korea continues work on key missile bases

CNN images reveal that North Korea has been upgrading its Yongjodong missile base and constructing a new facility nearby. The large underground facility, under construction since 2017, is strategically located to house long-range missiles capable of carrying nuclear warheads. Additional infrastructure, including shelters and tunnel entrances, is being built to support missile deployment.

What capabilities do the missiles mentioned in the text possess?

What types of shelters are reportedly being constructed for the vehicles carrying the missiles?