Module 15: Nuclear Weapons and US Foreign Policy II

What is the problem of credibility in nuclear deterrence, and why does it matter?

Credibility means an enemy must believe your threat is real. If a state’s threat to use nuclear weapons isn’t believable, deterrence fails. Once war begins, incentives change—so the enemy might doubt you’d actually use nuclear weapons.

What is extended deterrence, and how does it create credibility problems?

Extended deterrence is using nuclear threats to protect allies (like the U.S. protecting Europe during the Cold War). It’s less credible because it’s hard to believe a country would risk its own cities (like Washington or New York) to defend another country (like Paris or London).

How is credibility based on capabilities and resolve?

• Capabilities: Having the weapons and technology to follow through on a threat.

• Resolve: Having the will to actually use them if necessary.
  Both are needed for threats to be believed.

How does a state demonstrate credibility in nuclear deterrence?

• Brinkmanship: Willingness to risk war to show seriousness.

• Tripwire forces: Small troops placed in danger zones to guarantee retaliation if attacked.

• “The threat that leaves something to chance”: Creating uncertainty to make threats seem riskier and more believable.

• Public pronouncements (especially by democracies): Leaders’ public commitments increase the cost of backing down.

How might national missile defense (NMD) affect the stability of nuclear deterrence?

NMD could shoot down nuclear missiles, undermining mutually assured destruction (MAD).

• The state with NMD might feel safer and more willing to strike first.

• The state without NMD might build more nukes or strike before defenses are ready.
  → This makes deterrence less stable.

What was the Strategic Defense Initiative (SDI), and what replaced it?

SDI was Reagan’s plan for a massive missile defense system, but it was never built. Later, the U.S. adopted limited NMD—meant to stop small nuclear attacks from states like North Korea, not all-out wars.

What is nuclear proliferation?

The spread of nuclear weapons to more countries beyond the original nuclear powers.

Why do states try to get nuclear weapons, even with the risk of backlash?

• For security—to deter stronger enemies.

• For domestic political reasons—to boost national pride or government support.

• To challenge international norms and gain power or prestige.

Why do nuclear states and the international community want to prevent proliferation?

• New nuclear states have fewer weapons and unstable governments.

• Higher risks of accidents, terrorism, and regional arms races.

• More nukes = greater chance of global instability.