This link is the only thing I can find on this subject. I think it means nuclear weapons being used by stable or unstable states.
In this case nuclear deterrence means the use of nuclear weapons as a threat against those who may be considering launching a nuclear attack. To stabilize such a situation the idea is to slow down the continuous and unending manufacture of nuclear weapons for the sole purpose of merely trying to intimidate you opponent. As some point rational men must look at each other and say," this is getting out of hand, can't we both agree to stop trying to out do the other in seeing who can build the most bombs, we've already got enough to destroy the entire planet multiple times over."
The SALT treaties were a series of negotiated treaties between the US and the USSR to reduce the number of nuclear warheads held in each other's arsenals
I know this is old but none of the current answers suitably answers the question and as this is a top result on google I thought I'd respond.
Stability in nuclear systems is how much value is placed on a first strike vs retaliation.
Some systems place significant value on a first strike (Land based systems, missile defence systems etc.. read more on Wiki - Pre-emptive Strike) These are DESTABILIZING as they are significantly less effective in retaliation and therefore more likely to be used to initiate nuclear war.
Other systems such as submarine based ICBMs are effective as a response to aggression from another state, they are therefore STABILISING as the state holding them has less incentive to strike first and making hostile states unlikely to attack for threat of retaliation and MAD, therefore reducing the probability of initiating nuclear war.
To cut it's energy level off
MAD and equality.
Does it mean to make nuclear deterrence more-so where there is every less fighting, or to eliminate it? Also, how did SALT help do this?