I watched a video about tunnels in US from here last night. I'd look for it sorry I don't have link but it was posted last night with link.

Gene Decode has the good info on dumbs.

If you got to Brighteon.com and search DUMBS there is good info. https://www.brighteon.com/dee2cc90-545b-4fd1-b572-aaa98a6eeba1

I found a "DUMBS" file on my computer from April 2020 containing many links.

http://www.thetruthdenied.com/news/2012/12/14/complete-list-of-military-underground-bases-in-usa/

https://www.militarytimes.com/news/your-army/2019/02/26/the-subterranean-battlefield-warfare-is-going-underground-into-dark-tight-spaces/

https://www.military.com/daily-news/2018/06/24/army-spending-half-billion-train-troops-fight-underground.html

https://sputniknews.com/military/201806251065742558-US-Army-Training-Underground-Combat/

https://www.gizmodo.com.au/2014/02/training-for-underground-warfare-at-a-nuclear-weapons-complex-in-texas/

https://popularmilitary.com/us-army-training-soldiers-fight-subterranean-warzones/

https://www.timesofisrael.com/idf-paratroopers-teach-us-marines-lost-art-of-tunnel-combat/

https://www.defenseone.com/technology/2018/06/underground-may-be-us-militarys-next-warfighting-domain/149296/

https://taskandpurpose.com/news/army-subterranean-warfare-training

https://www.popularmechanics.com/military/weapons/a14456933/the-us-army-is-training-to-explore-fight-in-north-koreas-maze-of-tunnels/

https://www.npr.org/2018/01/09/576542410/as-north-korea-tensions-rise-u-s-army-trains-soldiers-to-fight-in-tunnels

https://mwi.usma.edu/elephant-tunnel-preparing-fight-win-underground/

https://taskandpurpose.com/military-tech/army-robots-subterranean-warfare

http://www.leatherneck.com/forums/showthread.php?60477-Marines-build-warfare-training-city-in-desert

https://mwi.usma.edu/fixing-way-army-trains-urban-warfare/

https://en.wikipedia.org/wiki/Tunnel_warfare

https://smallwarsjournal.com/jrnl/art/swj-book-review-underground-warfare

https://www.desertsun.com/story/news/2015/09/04/marines-train-urban-warfare-simulated-scenarios/71729350/

https://www.lawfareblog.com/fighting-tunnels

https://www.businessinsider.com.au/darpa-underground-spaces-prep-urban-warfare-2019-8?op=1&r=US&IR=T

https://www.businessinsider.com.au/trump-pushes-for-space-force-as-us-army-preps-for-underground-warfare-2018-8/?op=1&r=US&IR=T

https://www.airforcetimes.com/news/your-military/2019/02/26/tunnel-warfare-will-test-the-air-forces-ability-to-spy-and-bomb-a-hidden-enemy/

https://www.airforcetimes.com/news/your-air-force/2019/03/12/the-air-forces-struggle-to-fight-subterranean-warfare/

https://www.nationaldefensemagazine.org/articles/2002/10/31/2002november-navy-sets-up-new-facility-for-tunnelwarfare-training

https://qz.com/1175447/north-korea-the-us-army-is-training-to-fight-in-tunnels/

https://www.ausa.org/articles/facing-our-underground-nightmares-casting-light-subterranean-fight

https://www.newsweek.com/us-war-north-korea-tunnels-775209

https://www.c4isrnet.com/unmanned/2019/06/03/how-the-military-could-find-robots-it-needs-to-win-underground/

https://www.defenseone.com/technology/2017/12/pentagon-launches-new-push-tunnel-warfare-tech/144748/

https://military.wikia.org/wiki/Tunnel_warfare

https://defense-update.com/20140727_subterranean_ops.html

https://www.breitbart.com/middle-east/2018/03/14/marines-train-israeli-military-urban-warfare-drill/

https://www.popularmechanics.com/technology/design/g152/strangest-military-bases-gallery/

https://www.fpri.org/article/2015/04/fighting-under-the-earth-the-history-of-tunneling-in-warfare/

https://www.washingtonpost.com/news/checkpoint/wp/2014/07/21/hamas-tactics-highlight-u-s-militarys-preparation-for-tunnel-warfare/

https://apps.dtic.mil/docs/citations/ADA620416

https://mwi.usma.edu/underground-warfare-wish-list/

https://global.oup.com/academic/product/underground-warfare-9780190457242?cc=au&lang=en&

https://mwi.usma.edu/war-books-preparing-underground-warfare/

https://www.law.columbia.edu/events/underground-warfare

https://callofduty.fandom.com/wiki/Underground

https://roblox.fandom.com/wiki/Community:Stickmasterluke/The_Underground_War

https://youtu.be/ylkEfC-CoyIYouTubeYouTubeYouTube

https://survivalschool.us/survival-info/military-manuals-pdf/

https://www.reddit.com/r/DrainTheSwamp/comments/8v1xnj/underground_warfare_happening/

DUMBs and Billionaire Bunkers: >

https://www.youtube.com/watch?v=cLy6AXjwQK8YouTubeYouTubeYouTube

https://www.youtube.com/watch?v=bAOj7pMXVgI&list=PLdB5_JQvO-7KLUOolEkAjrrhZMJgYWjHt&index=20YouTubeYouTubeYouTube

https://www.youtube.com/watch?v=4LuHqhNEKqkYouTubeYouTubeYouTube

https://www.youtube.com/watch?v=BQtjZFUyvSAYouTubeYouTubeYouTube

https://www.youtube.com/watch?v=L8jU67dOH7kYouTubeYouTubeYouTube

https://www.youtube.com/watch?v=qnL63lEceDEYouTubeYouTubeYouTube

https://voat.co/v/QRV/3679875

https://supersoldiertalk.com/15188-2/ Rumors were swirling in NYC too when hospital ships Comfort and Mercy arrived. Tunnels are everywhere filled with poor souls who are experimented on. Dr. Mengel like atrocities. These poor souls.

https://wearechange.org/theres-hidden-network-tunnels-underneath-washington-dc/

https://thefreethoughtproject.com/secret-tunnels-washington-dc-suburb-millionaire/

They've been digging tunnels under DC ever since there was contraband and trafficking - oldest ones go back to early 1800s. Interesting history. Bootleggers, slaves, underground railroad, etc. Traffickers love tunnels.