All of America’s elite special operations units are accustomed to operating under a veil of secrecy, but few units are more adept at secret keeping that the U.S. Army’s 1st Special Forces Operational Detachment-Delta, or Delta Force, as they’re often called. Since its very inception, Delta was intended to be a force like no other — utilizing a large officer corps and extensive and highly specialized training to produce an elite unit of war fighters that can operate at the very forefront of America’s defense apparatus. The men (and likely women) assigned to Delta are often called upon to serve as the literal instruments of America’s foreign policy, often in secret and without any form of direct support.

Perhaps it’s because of the high degree of secrecy employed by special operations units like Delta that they often come up in discussions about secret government projects, cover ups, and conspiracies. To be fair, sometimes there’s truth to be found in rumors about secret military operations on U.S. soil and beyond. The American government has a long and storied history of developing black projects that go on to serve as the backbone of its defense apparatus — from stealth aircraft to nuclear weapons — and it stands to reason that some programs are developed in cooperation with or supported by special operations troops.

Despite the long list of legends that either are true or are probably true, there are also other stories that find their way into the cultural lexicon, hanging on over the years despite their silly seeming premise. These stories often involve darker elements than scientific research or classified regime changes. Such is the case with reports of a secret base deep beneath the small town of Dulce, New Mexico — where, according to a passionate contingent of internet sleuths and UFO researchers, special operators found themselves in a firefight with aliens from another world.

Tale of the “D.U.M.B.” (Deep Underground Military Base) beneath Dulce, New Mexico may have started with a man named Philip Schneider. Schneider allegedly worked for the U.S. military in the 1970s as an engineer, helping to construct a massive network of underground installations connected by subterranean tunnels. According to the stories Schneider has told, he first became suspicious about the new tunnels they were building when he noted the presence of American special operations troops in the vicinity. Depending on the recording and source, those troops hailed from either specifically Delta Force or Army Special Forces (Schneider seems to go back and forth on this point).