How wide of a range can a nuclear missile affect?

Answer 1

For warhead blast damage, the initial blast radius is dependent on the warhead yield (kilotons or megatons), the higher the yield resulting in a wider range of destruction. The calculation even for the initial Trinity bomb test was a rough one, estimated to be about 22 kilotons.

The Radius (R) of the blast depends on 3 primary factors in the equation first used to calculate the yield of the Trinity test by- Energy released (E), Time after detonation (how fast the explosion has expanded in a certain amount of time) (T), and the Density of the air where the explosion takes place (P).

However, Alpha radiation contamination from the blast fallout can circle the globe driven by the weather. For this reason, the main nuclear powers in 1963 (U.S., UK and the USSR) signed the Limited Test Ban Treaty, which banned all above ground testing when it was found that fallout from air and ground testing up to that resulted in contamination of food supplies (high levels of Strontium 90 were detected in pasteurized milk, e.g.).

As for a missile's tactical range, it depends on the range of the delivery vehicle itself. Tactical nuclear weapons typically have a range in the hundreds of miles (Tomahawk TLAM-N or ALCM-N, e.g.) while short range weapons are typically under 100 miles. Strategic weapons (ballistic missiles) typically range in the 4,000-8,000 mile range. Most actual weapons range limits are classified for obvious reasons (Peacekeeper range is "greater than 6k miles, e.g.), but its widely known that most ballistic missiles have global target range.

It's important to remember also that ICBM's take the shortest route to the target, and that's not horizontally across the globe as some games and movies have mistakenly shown. Targeting is typically over the North Pole (U.S. and Russia) or from a southern point to a northern one and back down to the target. This is because it's a shorter range of flight time this way, due to the circumference of the Earth being shorter at higher latitudes.

During the Cuban Missile Crisis, the focus was on Strategic Nukes that had a flight time of less than 30 minutes to Washington, and about 5min to Florida. What was not known at the time and only learned at a much later date was that the Soviet Union had also installed Tactical Nuclear Weapons in Cuba. Had the U.S. decided to invade, the result would've been disaster as those weapons were operational and had not been picked up by the U-2 surveillance.