"Curiously, there aren’t many political concepts Americans have borrowed from Turkish history, but the deep state seems to be one of them.

The Turkish phrase derin devlet literally means “deep state.” According to historian Ryan Gingeras, the term “generally refers to a kind of shadow or parallel system of government in which unofficial or publicly unacknowledged individuals play important roles in defining and implementing state policy.”

This concept of a deep state, Gingeras continues, is used to “explain why and how agents employed by the state execute policies that directly contravene the letter and spirit of the law.” Breaking the law, of course, often means employing criminals. Gingeras, a specialist in organized crime in Turkey, looks at the underbelly of the Turkish deep state to examine how alliances between generals, statesmen and “narcotic traffickers, paramilitaries, terrorists, and other criminals” are formed. (Elsewhere, Gingeras traces the heroin connection, noting that the Turkish deep state itself is riven by factional rivalries.)"

https://daily.jstor.org/the-unacknowledged-origins-of-the-deep-state/

The term entered into English via former Canadian diplomat, poet, and Berkeley professor emeritus of English Peter Dale Scott, regarding the Susurluk scandal (https://en.m.wikipedia.org/wiki/Susurluk_scandal)
that followed the crash of a Mercedes into a flatbed truck in that town northwest of Istanbul in the late 90’s late one night, killing all but one passenger, including 3 men supposed to be arch enemies, the assistant police chief of Istanbul, the leader of the Kurdish faction in the Parliament, and a world-class drug lord and murder for hire expert Abdullah Çatlı, the leader of the Grey Wolves (who was a contract killer on Interpol's red list) along with his movie star girlfriend.

Prior to this, Çatlı (pronounced Chutluh) had escaped from a Swiss prison with the aid of a helicopter — a NATO helicopter.

When the state police learned of the incident they rushed to the scene but too late because the local police had already investigated and it was all over the papers. Turkey learned that day that they were governed not by the public state but by a deep state. The US, indeed the West, has yet to learn this fact about its own countries.

Çatlı's operation, the Gray Wolves, is often described as the beginnings of Gladio-B, a Turkish and Central Asian continuation of the NATO intelligence program known as Operation Gladio in the 60s, 70s, and 80s, which implemented what they called the "strategia della tensione", with dozens of bombings of banks, school buses, train stations, and any venue that would raise public ire and anxiety. In this clip from the BBC, Vincenzo Vinciguerra, interviewed in his life cell in prison for the Peteano bombing, explains the motive behind the strategy.