What is an Intercontinental Ballistic Missile (ICBM)?

Intercontinental ballistic missiles (ICBM) are a country’s nuclear weapon system. ICBMs have a minimum range of 3,100 miles (5,000 km).
Interesting Engineering

World War II was a period of great suffering for many countries worldwide. Millions of combatants and civilians were slaughtered in their millions on land, at sea, and in the air. 

But it was also a period of incredible technological improvement. Jet engines became viable, medicine was revolutionized, true computers emerged, and the atom was split. 

And one other technology emerged, rockets. 

Born from Germany's desire to deal death at a distance, the early "Vengeance Weapons" of the Third Reich culminated in creating the first long-range, large payload rocket platforms, the V2 rockets. 

Terrifying and impressive in equal measure, these rockets became the basis of feverish study in the postwar period. After years of study, and trial and error, these early rockets would evolve into enormous missiles capable of launching humans into space or delivering humanity's newest mass destructive weapons halfway around the world.

The era of the Intercontinental Ballistic Missile (ICBM) had arrived. 

Able to send multiple nuclear warheads into Earth's orbit to rain down on the world below, these missiles would dictate national defense strategies for most of the world's great powers for decades to come. 

Early examples like the United States famed "Minuteman" ICBMs would lead to 40 years of a tense standoff between the East and West with the promise of mutually assured destruction, or MAD for short. Later improvements would enable ICBMs to be deployed inside submarines, but ultimately their main purpose would remain the same; the promise of complete devastation to an enemy's cities without risking soldiers' and pilots' lives.

But, with the "Cold War" over, many have questioned whether ICBMs have outstayed their welcome. Large, relatively slow, and expensive to maintain and build, could more recent developments in rocketry, like hypersonic missiles, mean the end of the ICBM? 

If recent news from the United States is any indication, it appears not. 

The United States Air Force has recently contracted Northrop Grumman to replace its aging ICBM stockpile with a new Ground-Based Strategic Deterrent (GBSD) called "Sentinel."

Effectively thoroughly modernized versions of the current "Minuteman III" ICBMs, this new system emphasizes future-proofing current missile stockpiles and facilities. The new ICBMs will be more modular, enabling them to be quickly modernized over time. 

Over time, this will make maintaining and upgrading them a lot more cost-effective in the future. This will reduce the cost of maintaining and upgrading them over time. If implemented, it should allow the GBSD system to remain viable well into the 2070s. 

GBSD also aims to dramatically improve launch facilities and command and control systems, and increase the safety and security of the United States' nuclear deterrent. 

In a world where the threat of nuclear war is rearing its head again, innovations like GBSD could arguably be well overdue. 

Let's just hope they will never have to be used for real.