The United States has decommissioned the last of its Peacekeeper missiles. These were the larger of the two kinds of intercontinental nuclear missles in the American nuclear arsenal. Each carried warheads capable of hitting ten different targets. For many years, the United States had maintained 50 of them, but they have been eliminated in response to disarmament treaties reached with Russia in 2001. Russia has also cut its arsenal.
Once again, the trend is away from sledgehammers and towards jeweler's screwdrivers. The treaty with Russia was made possible when U.S. military planners recognized that they didn't have a good reason to completely destroy innocents and combatants alike ten different major foreign cities with a single missile. Now, if the U.S. wants to obliterate foreign cities, it has to do so one at a time, up to five hundred times, before it has to turn to aircraft and submarine based missiles.
The U.S. has no imaginable coalition of opponents who have that many significant sized cities. Neither Russia, nor the United States, have any meaningful protection against intercontinental ballistic missiles with nuclear warheads (nor does any other country). So, basically, every nuclear missile fired will hit and destroy its target.