>>12585578 /lb

I think I found the source for the pics.

BY STAFF SGT. MICHAEL ARMSTRONG

2nd Brigade, 2nd Infantry Division Public Affairs published these pics @ https://www.dvidshub.net/image/4406628/lancers-train-participate-subterranean-operation

Soldiers of 2nd Stryker Brigade Combat Team, 2nd Infantry Division, prepare to clear a corridor during subterranean operations training, May 17. Lancers of 2nd Stryker Brigade Combat Team, 2nd Infantry Division, with the assistance of a Mobile Training Team from the Army’s Maneuver Center of Excellence, completed a 5-day exercise focused on subterranean operations, at a remote underground facility in Washington State, May 14-18. (U.S. Army photo by Staff Sgt. Michael Armstrong, 2SBCT, 2ID)

He also wrote about it here: http://www.northwestmilitary.com/news/news-front/2018/05/Taking-the-fight-underground/