Extended Deterrence

The threat to retaliate against an adversary with nuclear weapons on behalf of a third-party is called extended deterrence, and is sometimes referred to as the nuclear umbrella. Through military alliances, such as the North Atlantic Treaty Organization (NATO), and other mutual defense treaties, the United States has agreed to extend its nuclear umbrella over its allies and friends. During the Cold War, the Soviet Union entered into similar arrangements with its allies.

The U.S. nuclear umbrella in particular has provided many industrially-advanced countries with the option to choose not to develop WMD, even though most are technically capable of doing so. "The National Security Strategy of the United States" (March 2006) reiterates the importance of maintaining credible nuclear forces as a deterrent against threats to the United States and its allies. This policy states that the United States' New Triad will "bolster security commitments" to U.S. allies, and aid nonproliferation objectives by convincing these countries not to build their own nuclear weapons programs. Extended deterrence offers one possible reason for states not to proliferate.

Further Reading:

	CNS, Baker Spring, "The Implications of the Nuclear Posture Review for Extended Deterrence"
	The Washington Quarterly, Kathleen McInnis, "Extended Deterrence: The U.S. Credibility Gap in the Middle East"
	CATO Institute, Jeffrey Record, "Nuclear Deterrence, Preventive War, and Counterproliferation"
	Natural Resources Defense Council, "U.S. Nuclear Weapons in Europe"