Last Saturday, 70 operators hailing from Delta Force’s A Squadron and the 75th Ranger Regiment stormed a compound in the Idlib Province of Northeast Syria, successfully neutralizing one of history’s most despotic leaders, Abu Bakr al-Baghdadi. The story made headlines around the world, but among those who aren’t as well versed in the makeup of America’s special operations units, one question kept popping up… What exactly is Delta Force?

While it could be said that every unit which falls under the “special ops” umbrella is comprised of operators who can move, shoot, and communicate with lethal efficiency, different units were created to address specialized challenges. As the years wore on, and particularly since the onset of the Global War on Terrorism, lines may have blurred a bit between specialties in many cases, allowing various units to conduct similar operations. But, the specific nature of each continues to inform the internal culture of divisions that fall under the command of U.S. Special Operations Command (SOCOM), honoring their heritage as well as the prowess their service experience allots.

Aside from a 1986 Chuck Norris movie, most folks that aren’t affiliated with the military likely have little idea of what Delta Force actually is. The Unit (as it’s sometimes called) is often mentioned alongside the far more publicly understood SEAL Team 6, and for good reason. In a very real sense, Delta and ST6 represent the most elite and highly trained special operations warfighters on the planet, and both of these elite units fall under the same SOCOM subordinate command, JSOC, or the Joint Special Operations Command. Unlike ST6, however, which recruits only from within the SEAL community, Delta recruits across all branches. As a result, some former SEALs have even gone on to become Delta operators.

Delta’s elusive reputation can be credited to their secrecy. In fact, the name Delta is a misnomer, as the unit has actually changed titles repeatedly in his forty-plus year history. Originally called 1st Special Forces Operational Detachment-Delta (SFOD-D), later called Combat Applications Group (CAG), and then changed again in the late 2000s to Army Compartmented Elements (ACE), the name isn’t really all that important. Delta isn’t in the business of leaving calling cards. As demonstrated last Saturday, Delta is in the killing-bad-guys business (often referred to formally as Counterterrorism), and they’re damn good at what they do.

The Unit was first proposed in 1977 when the Army recognized the need for “an organization which can be deployed worldwide and has the capability to provide an appropriate response to highly sensitive situations including acts of international terrorism.”

“The proposed organization will provide a high specialized force, rich in rank structure, built upon small teams which contain mature, professionally trained, psychologically prepared individuals capable of making on-the-spot judgments,” the analysis read. The Army, bolstered by the guidance of Col. Charlie Beckwith, who had previously served alongside the United Kingdom’s 22nd Special Air Service Regiment in Malaysia, went ahead with planning the establishment of this new highly specialized unit that same year, with its official strength broken down to a planned 21 officers and 151 enlisted soldiers.

Those troops were further broken down into groups relating to their roles within the overall structure, with 12-man operational units called Operational Detachment As, or A-Teams that served as the backbone of the Unit’s fighting capabilities. The makeup of Delta was also unusual by design, with more higher-ranking officers than you’d find in other similarly sized units in order to lend Delta operations a higher degree of operational and intellectual maturity. As a result, Delta disallowed officers below the rank of Captain, and enlisted soldiers weren’t eligible until they reached the rank of Staff Sergeant.

“The highly sensitive nature of operations and degree of specialist training required fully justify this rank structure,” the analysis states. “The level of professional maturity required cannot be found in abundance among the first term enlistees and second lieutenants.”

Delta was an intensely secret unit right from the start. In fact, the Pentagon didn’t formally assign the unit to a mission until as late as 1990, but that’s not to say the Unit spent the intervening 13 years sitting on their hands. The nature of Delta’s work is secretive, and as such, the public doesn’t get to hear much about the missions they participate in very often.

Whether you call them Delta Force, CAG, ACE, or nothing at all, the mission of the Unit is simple: equipping elite war fighters with all the skills they need to serve as the sharpest edge of America’s foreign policy. For America and her allies, Delta may seem like little more than a whisper, but among America’s enemies, Delta is the sort of shadow that should keep you up at night.

Because this week it was al-Baghdadi. Next week, it might be you.