This simulation contains two parts: the attack, and the choices you make to explore different scenarios. The attack is shown on the map on the left of the display, and the choices in the column on the right. You can choose the attacker's weapons, the casualty figures, and the success of the defense.

Attack

Click the "Start" button to begin an attack. Choose an attacker to change the default settings of attacking weapons.

The map of North America is annotated with likely targets, the 20 largest US metropolitan areas. This simulation assumes the attacker targets the most populous areas first.

When the attack is completed, black circles show the attacked cities. The area of each circle is proportional to the number of casualties.

The log below the map records the cities attacked and the total casualties. The maximum number of casualties is 120 million -- the approximate total population of the top twenty cities.

Attacking Weapons

When you choose an attacker, default settings are chosen automatically for missiles, nuclear weapons, and other weapons. You can change any of these numbers to explore different possibilities. The choice of four attackers provides a range of scenarios.

Russia has thousands of long-range missiles and nuclear weapons. It is considered extremely difficult or impossible to create a missile defense system capable of stopping a Russian attack.

China has several hundred missiles and nuclear weapons. A US defense system could prompt China to expand and modernize its nuclear forces, starting a new arms race.

North Korea is often mentioned as a possible attacker. North Korea has a large military force. It is known to be developing both long-range missiles and nuclear weapons.

Iran is an example of a non-nuclear power with no long-range missiles. Such an attacker would be restricted to chemical, biological, or conventional weapons, and would attack across border defenses rather than a missile defense.

Missiles and nuclear weapons of these four attackers are approximately as estimated by the Federation of American Scientists.

Estimates of other weapons are chosen to provide a range of scenarios. These weapons can be simple conventional explosives, such as TNT; or something more exotic. All four potential attackers are known to possess chemical and biological as well as conventional weapons.

Casualties per Weapon

The Physicians for Social Responsibility has estimated casualties for a nuclear attack on a medium-sized city. In a city of 2.8 million, it is estimated 2.1 million would be killed immediately. Another 500,000 would be wounded by the blast, and an unspecified number would suffer the effects of radiation sickess or fallout.

This report estimates the effects of a nuclear weapon with a yield of 20 megatons, equivalent to 20,000,000 tons of TNT. Today's weapons are capable of greater yields.

Casualties from other weapons could vary widely depending on the type of weapon. The 2001 attack on the World Trade Center resulted in thousands of casualties.

Defensive Success

A complete defense must repel attacks from any delivery system. Therefore this simulation provides both missile defenses and border defenses.

Missile defenses repel attacks by ballistic missiles. A ballistic missile's path is determined by gravity, once its initial thrust is cut off. Ballistic missile defenses are prohibited by the ABM treaty.

Border defenses repel attacks by all other delivery systems. Such delivery systems include:

• cruise missiles, which can fly under an ABM defense
• airplanes, used in the 2001 World Trade Center attack
• trucks, used in the 1993 World Trade Center attack.

Perhaps the most dangerous delivery system is enemy agents crossing the US border. In 1994, the Department of Justice estimated that illegal immigrants in the US increased by 275,000 each year. It is of course not sufficient to stop only the illegal immigrants -- most of the World Trade Center terrorists entered this country legally.

One way to estimate defensive success rates is to consider success rates in the war on drugs. For many years, the US government has made a determined effort to stop drugs from entering this country. In 1997, the UN Drug Control Program estimated that 30% of worldwide cocaine shipments were intercepted, and 10-15% of worldwide heroin shipments. In 2001, Dr. Peter Reuter, writing in the Washington Post, estimated that 25-40% of US cocaine shipments were intercepted, and 10% of US heroin shipments.

Based on such estimates, defensive success rates of 30-40% appear reasonable. As with all choices in this simulation, you should change these numbers to explore different possibilities.