Rodents hold a prominent place in spy culture. “Secret squirrels” is an endearing name for those who work in intelligence. “Rats” are those who betray the confidence of those who’ve trusted them. “Moles” (technically a mammal, but indulge me) are trusted insiders who are secretly feeding information to the adversary. But have you ever heard anyone in the intelligence community talk about MICE?

MICE stands for “Money, Ideology, Compromise, and Ego” – a handy acronym that summarizes the motives of turncoats. It’s one of the concepts Edward Jay Epstein discusses in his 2017 book, How America Lost Its Secrets: Edward Snowden, the Man and the Theft. Epstein offers a comprehensive look at the life and crimes of Edward Snowden, painting a portrait of an insider threat.

Though Snowden’s leaks may have been of historic proportions, his motives followed the same MICE playbook of all traitors. And as Epstein explains, insider threats usually sprout from a combination of MICE factors. Here’s a breakdown of the MICE standard that all cleared professionals should be on the lookout for.

Money:

If a person with privileged access to information needs money badly enough, they may be tempted to sell government secrets to keep themselves afloat. That’s why financial reasons are so consistently the top cause of security clearance denial or revocation; people do foolish things when they’re strapped for cash. One of the most famous instances of this was the defection of Aldrich Ames, who sold out to the KGB to pay for his expensive divorce and lavish lifestyle of his new wife. Similarly, Robert Hanssen’s over 20-year betrayal to the Soviets began out of a financial need.

It seems straightforward, but money rarely travels alone in the MICE scenario; it usually precedes a much deeper motivation, which we’ll get to.

Ideology:

One of the most valuable resources to an adversary is the spy who volunteers himself – the “walk-in.” While some spies volunteer their services in exchange for money, many volunteer out of ideological sympathy with their adversary. Oleg Gordievsky, a KGB agent and longtime mole for MI6 during the Cold War, was motivated purely by ideology. As he served in KGB posts in Western nations, he became increasingly disillusioned with the Soviet way of life. More recently, Monica Witt betrayed the U.S. to Iran due to her disagreement with America’s Middle East policy and conversion to Islam.

Edward Snowden also had ideological disagreements with the tactics of the U.S. intelligence community. The lengths he has gone to paint himself as a whistleblower and a voice for internet freedom are proof. (They’re also proof of another MICE category). As an avid proponent of internet anonymity, Snowden evangelized the use of Tor software for years, which makes it possible for users to communicate anonymously online. He organized events with other hackers to discuss the government’s web surveillance techniques. Snowden’s motives were at least partly ideological.

Compromise (or coercion):

Compromise can be one of the more salacious – and unstable – motivations for cooperating with the enemy. After all, a spy motivated to turn over secret information at the threat of force or blackmail is not going to be the most loyal or cooperative spy. Nevertheless, digging up compromising information or threatening someone’s life has been used since time immemorial to entrap enemy spies.

One recent instance of this tactic was by the Chinese Ministry of State Security (MSS) on American student Glenn Duffie Shriver. While living in China as a student, Shriver was recruited by the MSS for a seemingly benign job: writing essays on U.S.-China relations. He met with someone he thought was an adviser and was paid with envelopes of cash. As the plot unfolded, the MSS tried to get Shriver to return home and apply for jobs with the U.S. intelligence community where he would work as their “man on the inside.” By the time Shriver realized what was happening, the MSS already had pictures of him meeting with Chinese operatives and accepting envelopes of cash – and voila! This accidental (but failed) spy was compromised.

Ego:

In the world of insider threats, money may be the shot, but ego is usually the chaser. Epstein’s book makes the very solid case that Snowden’s actions were motivated primarily by ego. He was embittered that he was not offered a job as an SES with the NSA (even though he was in his twenties and had no high school diploma). For this and other reasons, Snowden felt his talent was not sufficiently recognized by his superiors. But as the star of documentaries, Hollywood films, and the menagerie of Vladimir Putin, he has gotten to prove to the world just how brilliant and special he is.

He’s hardly the only turncoat to be reeled in by ego – take it from the Victor Cherkashin, the KGB handler who recruited Aldrich Ames and managed Robert Hanssen.

As Epstein writes, interviewing Cherkashin:

“When assessing Ames’ biographical data, Cherkashin said he was looking for a well-placed intelligence officer who was both dissatisfied with and antagonistic to the service for which he worked. ‘Any intelligence officer who strongly feels that his superiors are not listening to him and that they are doing stupid things is a candidate.’ He [Cherkashin] said that he had found that the flaw in a prospect that could be most dependably exploited was not his greed, lust, or deviant behavior – but his resentment over the way he was being treated. ‘The money we gave, even if he could only spend a small portion of it, gave him a sense of worth.’ He explained that the KGB had an entire team of psychologists in Moscow that worked on further exploiting Ames’ resentment against his superiors.”

Such was certainly the case for Hanssen, as well. Because of his caustic personality, he failed to rise up the ranks and be appreciated for his legitimate genius. That bitterness fueled over 20 years of Hanssen’s betrayal and one of the most devastating breaches in U.S. history.

So what’s the takeaway? Pay attention to those around you. Is your coworker up to his ears in debt? Is someone making anti-government comments on their social media? What about that “underappreciated genius” who thinks everyone else is an idiot? Be careful: you may just have some MICE on your hands.