The American military is looking at how its land-based nuclear missile system will work post-2025. Sharon Weinberger described the ideas being discussed so far:

• Nuclear weapons are all about deterring the enemy from daring to hit you in the first place, and so it’s important to convince the enemy that even if they manage to strike the country, the United States can still launch an annihilating counter-attack.
• The current system does this by spreading nuclear missile silos across a vast expanse of land.
• However this system is expensive and requires the maintenance of lots of missile silos dispersed across wide ranges.
• An alternate idea would have a nuclear ‘subway’ that would randomly transport nuclear weapons through various underground tunnels. The enemy would thus never know precisely where the missiles are.
• Another idea would have the missiles transported on specialized vehicles that would venture on public roads or even into off-road areas to prevent the weapons from becoming a static target.

Read more about other ideas, as well as the idea that the military is most likely to pursue over here.

Source: BBC