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Prisoner’s Dilemma and Deterrence Activity


This activity complements the teacher’s lesson on deterrence and nuclear weapons during the Cold War. Students will learn the logic behind deterrence theory and Mutually Assured Destruction. In the advanced version, students will look closer at today’s U.S. deterrence strategy.

Terms Learned: game theory, Prisoner’s Dilemma, Mutually Assured Destruction (MAD), deterrence, deterrence by force, deterrence by denial, deterrence by force, Nuclear Triad, extended deterrence

Secondary Terms: rational actor, second-strike capabilities


Materials: Quarter, character cards, script

Helpful visual aid: Prisoner’s Dilemma Chart


You both are guilty of breaking the potted plant. The INVESTIGATOR suspects that you did it and will question you separately. What will you do?


The INVESTIGATOR knows that PLAYERS 1 and 2 are guilty of breaking the potted plant but lacks evidence. Therefore, the INVESTIGATOR must question PLAYERS 1 and 2 separately to see if s/he can get the PLAYERS to flip on each other.


INVESTIGATOR: I know you and PLAYER 2 were the ones who broke the potted plant. But if you confess, the teacher will give you a lighter punishment.




Situation: Oh, no! Somebody broke the teacher’s potted plant! The INVESTIGATOR has an idea about who might have done it, but lacks proof…

Activity: First, the teacher will post or draw the Prisoner’s dilemma chart for students to consult throughout the activity.

Second, the teacher will call on 5 volunteers:

  2. PLAYER 1
  3. PLAYER 2
  4. QUARTER FLIPPER who determines the how PLAYERS 1 and 2 respond
  5. RECORDER who writes the results of each iteration

The teacher will give PLAYERS 1 and 2 their character cards and read them out loud and then explain the scenario.

The INVESTIGATOR will “question” PLAYER 1.

QUARTER FLIPPER will flip a quarter to determine how PLAYER 1 will answer. HEADS is CONFESS, and TAILS is DENY. Repeat for PLAYER 2. The teacher will announce the results (use the Prisoner’s Dilemma chart on the next page to help you). The RECORDER will write down how the PLAYERS answered and the “punishment.” Do this for several iterations.

  • Make sure to demonstrate the results of both PLAYERS DENYING and both CONFESSING

Explanation: This scenario should feel very familiar to most people since this type of situation is often portrayed on cop dramas. It is call “PRISONER’S DILEMMA,” which is part of GAME THEORY. Game theory is the study of interactions and decision-making among multiple, rational players, and Prisoner’s Dilemma answers the question of “Do I cheat or do I cooperate?”

Question: What was the best outcome for both PLAYERS? What was the worst?

  • The best outcome is when both players denied, and the worst was when they both confessed.

Question: Why might one or both players decide to cheat?

  • They don’t trust each other to cooperate and want a guaranteed reduced sentence (a 1-day detention is better than a 5-day detention).

Open-Ended Question: Why would both players decide to trust each other? Under what circumstances would they trust each other?

Explanation: When we conduct Prisoner’s Dilemma simulations, we do multiple iterations. This allows the players to better understand what the other is like. Each iteration answers questions like, “Is the other player trustworthy? Does s/he tend to cheat?” Over a period of time and after many iterations, the players develop a relationship (good or bad) with each other, and each player develops a reputation.


Explanation: Let’s look at the Prisoner’s Dilemma in a different way and ask the question, “What will I gain if I cheat?” Let’s say two countries have agreed to not to raise tariffs on each other’s goods. If both countries cooperate, then both will earn $3,000,000. However, if one country decides to cheat and raise tariffs, then it will earn a maximum of $5,000,000 while the other earns $0.

Question: What happens to Country A if it consistently cooperates? Consistently defects?

  • If Country A consistently cooperates, then it will develop a reputation of being trustworthy, and Country B is more willing to trade with it in the future. However, Country A will not earn the highest possible amount of $5,000,000 in a single iteration.
  • If Country A consistently defects, then it will develop a reputation of being untrustworthy, and Country B will be more unwilling to trade with it in the future. However, Country A will earn the highest possible amount of $5,000,000 in a single iteration.

Explanation: Now, let’s examine the United States and the USSR during the Cold War in terms of Prisoner’s Dilemma.

This chart only represents one hypothetical interaction between the United States and the USSR. If the USSR were to use nuclear weapons while the United States did not, then the USSR would win that round. However, because the USSR signaled that it was willing to use nuclear weapons and would probably do so again, the United States, in turn, would use its nuclear weapons in the next interaction. As such, if both countries used nuclear weapons, both countries would lose. How likely would it be for one or both countries to voluntarily stop using nuclear weapons? Not likely. Therefore, with each successive iteration, both countries would continue to use nuclear weapons and continue to lose.

Question: What is the best scenario for both the United States and the USSR?

  • Both don’t use!

Explanation: The hypothetical scenario in which the United States and the USSR use nuclear weapons in repeated iterations leads to the concept of MUTUALLY ASSURED DESTRUCTION, MAD for short, or the idea that consequences of using nuclear weapons are too unfathomable and too dangerous that neither country would use them. MAD goes hand-in-hand with the concept of DETERRENCE. There are many definitions of deterrence, but all these definitions have similar components:

  1. You want to influence your adversary into not taking a particular action by making the costs of taking that action unacceptable and denying any benefits of taking that action.
  2. Therefore, your adversary is the one who ultimately decides if they are scared enough by your military forces or not.
  3. This implies that all actors are rational.
  4. If your adversary is a rational actor, then it is possible for you to have to know exactly what your adversary is thinking. What motivates them? What scares them?
  5. You must clearly communicate that your weapons/weapons systems are for defense only.
  6. Your threats must be credible, and you must be willing to follow through on your threats.

There are three types of deterrence:

  1. DETERRENCE BY FORCE: the threat of retaliation
  2. DETERRENCE BY DENIAL: the denial of adversary’s objectives in taking undesirable action
  3. DETERRENCE BY NORM: the use of nuclear weapons is so unfathomable and so barbaric that no country actually wants to resort to using them


Explanation: The lack of use of nuclear weapons during the Cold War suggests the validity of MAD and deterrence. The United States did consider using nuclear weapons during the Korean War and the Vietnam War. Nuclear weapons would have completely and easily decimated enemy forces.  However, by not using nuclear weapons and, for the most part, relying primarily on conventional forces, the United States inevitably raised the threshold for nuclear use. Simply being in a state of war is not a good enough reason to use nuclear weapons. A much larger event or threat must take place to warrant the use of nuclear weapons. What that entails, nobody really knows.


Explanation: How do we know when deterrence is working? Some experts will tongue-in-cheek reply, “We don’t know if deterrence is working but we will definitely know when it fails.” Deterrence fails when one actor does not correctly assess the adversary’s motivations and fears or does not make credible threats. As a result, nuclear weapons are used.

The Cold War almost became a “hot war” with the Cuban Missile Crisis. Lack of clear communication and lack of understanding of each others’ motives contributed to the escalation of the situation. For example, the United States believed that neither the USSR nor Cuba would use nuclear weapons in the event of a U.S. military invasion of Cuba. After all, a nuclear war would result in a lose-lose-lose situation for all parties. However, former Secretary of Defense Robert McNamara learned decades later from a Cuban official that if the United States invaded Cuba, Havana would have ordered the use of nuclear weapons and risk the threat of total annihilation rather than to lose the weapons.

Fortunately, President Kennedy did not go through with a military invasion of Cuba and was able to open lines of communication with President Khrushchev to deescalate the situation.

Open-Ended Question: Does the Cuban Missile Crisis demonstrate a failure or success of deterrence?



Explanation: MAD is a Cold War concept that ended with the fall of the Soviet Union in 1991. Deterrence, on the other hand, is still a critical part of U.S. strategy. However, today’s deterrence strategy is vastly different from the deterrence strategy from the Cold War.

Question: What do you think are the reasons for today’s deterrent strategy being different from the Cold War’s?

  • The United States and the USSR were the dominant, nuclear forces that possessed nuclear weapons. Today, many countries possess them, such as India, Pakistan, Israel, China, Russia, and, now, North Korea. While France and the U.K. do have nuclear weapons, they are U.S. allies and do not necessarily need to be deterred.
  • The United States is now not only deterring against nuclear attacks but also biological, chemical, and cyberattacks (on critical infrastructure). For more information, please look at the 2018 Nuclear Posture Review.
  • The United States now must deter against terrorists, not just other states.

Explanation: What does U.S. nuclear deterrent strategy look like today? There are two major components: the NUCLEAR TRIAD and EXTENDED DETERRENCE. The NUCLEAR TRIAD is a three-pronged, military approach that provides SECOND-STRIKE CAPABILITIES (if a country attacks the United States with nuclear weapons, the United States would have the military capabilities to respond to the attack) in the event of a major nuclear, biological, chemical, or cyberattack on major infrastructures against the United States or its allies. The US Air Force controls the first leg, which is a ground-based intercontinental ballistic missiles (ICBM) called the Minuteman III. The US Navy controls the second leg, which are submarines that carry ballistic missiles. The US Air Force controls the last leg, which are bombers and stealth jets that carry conventional and nuclear weapons. The Nuclear Triad is supposed to provide the United States:

  1. Flexibility and various policy options
  2. Assurance that even if one leg fails, the United States can still effectively deter against threats
  3. Ability to also deter attacks against allies

Deterring attacks against allies is called EXTENDED DETERRENCE. Many countries fall under the “US nuclear umbrella,” including NATO countries in Europe, South Korea, and Japan.

More Resources:


Cuban Missile Crisis:

History of the Navy in the Manhattan:

Non-Proliferation, Limitation, and Reduction:

Nuclear Briefcase:

Strategic Defense Initiative:


“America’s Nuclear Triad.” Department of Defense Accessed October 19, 2018.

“Deterrence: what it can (and cannot) do.” NATO. Accessed October 19, 2018.

“Fact Sheet: The Nuclear Triad.” Center for Arms Control and Non-Proliferation. Published July 28, 2017.

Jennings, Nathan A. “Nuclear Weapons and the Korean War: A Precarious Beginning for the Tradition of Non-Use.” Small Wars Journal Accessed October 19.

Malone, Iris. “PS 114S. International Security in a Changing World Nuclear Weapons, Brinkmanship, and Deterrence: A Cheat Sheet.” Stanford University. Published 2016.

McNamara, Robert. Fog Of War Eleven Lessons From The Life Of Robert S. Mcnamara. Directed by Errol Morris. Original Release 2003; California: Sonny Classics, Video release 2004. Vimeo.

Mutually Assured Destruction? Game Theory and the Cold War” Cornell University. Published September 9, 2016.

“Nuclear Posture Review.” Department of Defense. Published 2018.

Pifer, Steven, and Richard C. Bush, and Vanda Felbab-Brown, and Martin S. Indyk, and Michael O’Hanlon, and Kenneth M. Pollack. “U.S. Nuclear and Extended Deterrence: Considerations and Challenges.” Brookings Institute. Published May 2010.

Sanger, David E. “U.S. General Considered Nuclear Response in Vietnam War, Cables Show.” The New York Times. Published October 6, 2018.

Shaw, Doug. “US Nuclear Strategy.” Lecture prsented at the Elliott School for International Affairs—The George Washington University, Washington, D.C., October 2018.

Tannenbaum, Benn. “How does the US use nuclear weapons?.” Lecture presented at the Elliott School for International Affairs–The George Washington University, Washington, D.C., October 2018.