Iran has its Furdow Nuclear Facility which is 80 meters under hard rock and special hardened cement. Iran claims to have built a military base that is under 500 meters of dirt and rock in a mountain range.

A facility 500 meters underground has entrances, air vents, radio antenna and other vital infrastructure that have ground level portions. Destroy them and you could isolate a bunker or even suffocate its inhabitants.

China has a massive nuclear bunker system that can hold 1 million people. The nuclear shelter system is up to 2000 meters deep and was built within a deep natural cave system.

Elon Musk's Boring Company recently completed a 1.25 mile tunnel in Los Angeles. In 2019, Elon Musk will start building a third generation all-electric tunneling machine which should be fifteen times faster. Currently, tunneling machines have about 20 meters per day speed. The third generation tunneling machine, Prufrock, will have a digging speed of about 300 meters per day.