Deterrence, doctrine and strategy
Deterrence is the rationale used by the nuclear weapons states to justify their weapons. The argument says that if a nation has capability to inflict unacceptable damage on another, then the latter will refrain from attacking the former—it will be deterred from doing so. The proponents of deterrence claim that it is responsible for the fact that there has been no war between the nuclear weapons states.
Given the nature of strategic nuclear weapons, deterrence relies on holding the civilian population hostage. Any peace created by deterrence is like the peace that exists between two persons who are holding guns to each other’s heads with their fingers on the triggers: an uneasy, tense peace which is fraught with danger.
For deterrence to continue to work perfectly and prevent a nuclear war which could end humanity, a number of things have to happen. For the rest of history, successful deterrence requires all those with the ability to launch nuclear weapons to engage in rational behavior and have rational opponents who fear death. Leaders must forever remain must remain rational in crisis situations which permit them only a few minutes to make world-ending decisions
The fact that no nuclear war has occurred in the last fifty years is no guarantee that it will not occur in the next fifty or hundred years despite deterrence. Only a single failure of deterrence is required to start nuclear war
Since a nuclear weapon can destroy a city within minutes of its being launched, it is necessary for a nuclear weapons state (at least one believing in nuclear deterrence) to clearly declare the circumstances under which it will use its weapons and the manner in which it will do so. This is its nuclear doctrine. The doctrine specifies if the state retains the option of initiating a nuclear attack (first use) or if it will use its weapons only in retaliation of a nuclear attack (no first use). The state also specifies the extent of use it will make of its nuclear weapons in different situations.
Planning for the use of nuclear weapons requires planning for mass murder. This is a morally corrosive exercise which ultimately corrupts the moral fabric of the rulers and society which engage accept and engage in it.
A nation which attacks another nation or enemy with nuclear weapons before it has been attacked with nuclear weapons is executing a nuclear first-strike. Nations which reserve the right to use their nuclear weapons preemptively (First Use of nuclear weapons) are saying that they would consider initiating a nuclear first-strike against their enemies.
Military planners in the U.S. and Russia still act as though each side would intentionally order a nuclear attack against the other. Thus each side keeps hundreds of missiles with thousands of warheads at high-alert, quick-launch status.
This is despite the fact that authoritative scientific research has predicted that even a “successful” nuclear first-strike against either opposing side (which destroyed the other’s ability to retaliate with nuclear forces) could easily cause deadly global climate change which would kill most people on Earth.
If a nation is subjected to a nuclear attack, it is presumed that the initial targets would be its own nuclear weapons facilities. A second strike capability means that the nation should have enough weapons and have them deployed in a manner that enough of them survive the initial attack and can be used for a retaliatory attack.
Thus the weapons that make up the second strike capability could be missiles that are launched from mobile launchers that are constantly on the move. Or they could be missiles launched from nuclear submarines which can stay submerged for long periods of time and are therefore difficult to locate and destroy.
The targets of a second strike attack would not be the empty silos of the attacking side, rather they would be the cities and industrial infrastructure where most of the enemy population resides. Thus a second-strike attack, even if were comprised of a limited number of surviving missiles, would cause enormous damage and destruction. As mentioned before, the environmental consequences of such a war would likely prove fatal to most people on Earth.