3. Delivery systems for nuclear weapons
The intercontinental ballistic missile (ICBM) is a ballistic missile with a range of more than 6,400 kilometers. It is a ground-launched missile, carries a hydrogen-bomb warhead over a typical range of around 10,000 kilometers. Together with the SLBM (to be explained next) and strategic bombers, it is one of the "three pillars" of strategic nuclear weapons
The development of the submarine-launched ballistic missiles (SLBM) has proceeded in conjunction with the development of nuclear-powered submarines. The ICBM is based in the possessor's own territory. Even ICBMs deployed in underground bases can be detected by other countries using reconnaissance satellites. As a countermeasure, SLBMs were built to be launched from nuclear submarines in constant movement around the oceans. Submarines are difficult to detect and able to enter areas near the enemy's territory. SLBMs are an important strategic nuclear weapon because they can escape a nuclear attack by the enemy and launch a counterattack.
*Nuclear submarines are classified into the attack-type SSN(nuclear submarines deployed with nuclear torpedoes targeting the enemy's warships and the enemy's nuclear submarines) and the strategic SSBN (loaded with SLBMs that target facilities thousands of kilometers away on the enemy's territory).

*Strategic bomber
Long-distance bombers played a greater role in the delivery of strategic weapons prior to the advent of missile systems such as ICBMs. Toward the end of World War II, B-29s (American strategic bombers) dispatched from Guam and Saipan ravaged major cities all over Japan, and B-29s carried atomic bombs to Hiroshima and Nagasaki. The maximum payload at that time was five tons.
The most advanced bomber developed by the US to date is the B-2. With a maximum speed of Mach 0.9 and a payload of 22 tons, it has a "stealth" structure that resists radar detection.

America's Strategic B-2 Bomber (Courtesy : NHK)
The Multiple Independently Targetable Reentry Vehicle (MIRV) carries three to ten nuclear warheads on a single missile (ICBM or SLBM), each of which can be set to attack different previously determined targets. Carrying multiple nuclear warheads (re-entry devices) and guiding devices, it launches a "bus" loaded with several small rockets. First, the three-stage booster rocket launches a bus toward the first target. The bus uses small rockets to direct individual warheads to the second, third, and subsequent targets. Like a bus letting off passengers at successive bus stops, warheads are launched one after another.
Missiles are classified by range as follows:
Intermediate-Range Ballistic Missile (IRBM): range - 2,400-6,400 kilometers
Medium-Range Ballistic Missile (MRBM): range - 800-2,400 kilometers
Short-Range Ballistic Missile (SRBM): range - up to 800 kilometers
*Cruise missile
While the ICBM and SLBM have rocket engines, the Cruise Missile has a jet engine. It is actually an unmanned aircraft that flies at a subsonic speed using an automatic guidance system. Before Okinawa reverted to Japan, the US military had a mid-range guided nuclear missile called Mes B. In recent years, the range of cruise missiles has leaped to almost 5,000 kilometers, making it a strategic weapon.
Cruise missiles include sea-launched cruise missiles (SLCM), air-launched cruise missiles (ALCM), and ground-launched cruise missiles (GLCM). Sea-launched missiles are launched from the torpedo tubes on submarines or warships. Air-launched missiles are deployed on strategic bombers where they can be launched from outside the range of enemy radar.

America's Strategic B-2 Bomber (Courtesy : NHK)