Missiles

Ballistic Missiles. A ballistic missile is a rocket capable of guiding and propelling itself in a direction and to a velocity that, when the rocket engine shuts down, will follow a flight pattern to a desired target. Ballistic missiles burn most of their propellant (fuel) in the initial portion of their flight, called the boost phase. Most fly fast enough to hit targets hundreds or thousands of miles away in a few minutes. Once launched, they are fairly easy to detect with radar or other sensors, but extremely difficult (some would argue practically impossible) to intercept. This is particularly true for missiles with longer range, such as intercontinental ballistic missiles (ICBMs).

Over 20 countries possess ballistic missile systems. Nations that have WMD usually seek to buy or develop ballistic missiles to deliver such weapons to enemy targets; the nine countries with nuclear weapons (the United States, United Kingdom, Russia, China, France, India, Pakistan, North Korea, and Israel) all have operational ballistic missiles. Only these nine countries and Iran have produced or tested missiles with ranges over 1,000 kilometers (km). These countries want such missiles because, at least to date, they could be certain of penetrating enemy defenses. For this reason, slowing the spread of ballistic missiles and developing defenses against them have become important elements of efforts to prevent the use of WMD. The latest U.S. Ballistic Missile Defense Review (BMDR), released in February 2010, highlighted the threat posed by regional ballistic missile threats, while maintaining the need to counter limited long-range nuclear strikes.

Cruise Missiles. A cruise missile is an unmanned, self-propelled, guided vehicle that sustains flight through aerodynamic lift (similar to an airplane) for most of its flight path. Like a ballistic missile, its primary mission is to place ordnance or a special payload on a target. One important difference between ballistic missiles and cruise missiles is that cruise missiles remain in the atmosphere for the entire duration of flight. Also, since cruise missiles rely on the thrust of their engines and aerodynamic lift, they may be controlled or even redirected during flight. Ballistic missiles, on the other hand, follow a path that is determined almost entirely during their initial boost phase and cannot be redirected during flight.  Many cruise missiles are capable of flying close to the ground and using other means to avoid detection by radar.

There are two main varieties of cruise missiles. The first are sea-launched cruise missiles (SLCMs), which are launched from submarines or surface ships. The second are air-launched cruise missiles (ALCMs), which are launched from aircraft, such as heavy bombers. Most cruise missiles carry conventional warheads. The United States, Russia, and China, however, deploy cruise missiles with nuclear warheads as well.

Further Reading:

	CRS, Paul Kerr, "Nuclear, Biological, and Chemical Weapons and Missiles: Status and Trends"
	CRS, Amy F. Woolf, "Conventional Warheads for Long-Range Ballistic Missiles: Background and Issues for Congress"
	CRS, Ronald O'Rourke, "Sea-Based Ballistic Missile Defense- Background and Issues for Congress"
	Arms Control Association, Missile Proliferation
	National Air and Space Intelligence Center, "Ballistic and Cruise Missile Threat"
	NTI, Dennis Gormley, "The Risks and Challenges of a Cruise Missile Tipping Point"
	U.S. Department of Defense, Ballistic Missile Defense Review 2010
	CRS, Steven A. Hildreth, "Iran's Ballistic Missile Programs: An Overview"
	Missile Defense Agency
	Multimedia:
	Ballistic Missile Test (Video)
	Tomahawk Cruise Missile (Video)
	NATO Multimedia, Missile Photos