One thing about Israel is that they usually take our technology and equipment and make it better and more lethal. Conflicts between allies of Russia against allies of the US do allow our designers and leaders to get an idea of how well our technology and weapons perform in direct competition with the enemy. So far we've done very well and the complete destruction of Iraq's Russian Tanks by our M1 Abrams tanks back in the 1990's sent Russian designers back to the drawing board fast and surely sent shock waves through the Kremlin as well as having China take notice. Technology is great though but some idiot fire off a Nuke and technology is quickly voided and sent packing. Let's just hope that our current Technology will be successful in intercepting any Nuke that North Korea might fire off.
The doctrine of M.A.D. has been great to keep the large parties/Nations honest and in negotiations but as mentioned there are wild cards out there that endanger all of us. North Korea account of pure insanity of it's way too young leader who surely is paranoid of many in his own regime and is unpredictable as to what he might do to remain in power. Then, yes, you have the Mullahs or Religious nuts over in Iran that I propose are much more dangerous than the Insanity of the North Korean leader. At least with North Korea you have China that might be able to achieve some restraint or control but with Iran you have people that honestly believe that with the use of Nuclear Weapons and a full unleashed Nuclear Attack be able to bring about the coming of their future Messiah/Mahdi. The Islamic religion, or some parts of it, actually believe that if they start a Nuclear War with Israel that Allah (god) will then send the Mahdi to take over the war and bring the entire Earth to convert to Islam.
The only similarity would be if Christians actually believed if they unleashed Nuclear Attacks against China or Russia that God would immediately intervene and take over the attack and stop all retaliatory responses from all opposing parties. In this case, as with Iran, it is very likely that these idiots will feel and believe they are doing a religious thing by destroying Israel, or trying, and thus if they have the weapons it is very logical that they would actually be tempted to use them without any provocation.
The other problem or trouble spot today is the conflict between two nuclear powers such as Pakistan and India over that small stretch of land over at Kashmir. Both India and Pakistan, nuclear powers, feel and believe that they could achieve defeat over each other without sacrificing their own leadership and control. That essentially is not the doctrine of M.A.D. but an actually mad (insane) thought and if actually they believe this then it is potentially a possibility that one of them would actually make a move on the other and only time would tell the outcome.
As for the major players and M.A.D. I think that will continue to work just as long as calmer heads do not allow some 3rd party conflict to escalate to the point that unreasonable and crazy irrational decisions are made and things happen so fast calmer heads don't have time to intervene and stop something before a point of no return is passed. There have been cases documented, in our past, even back to the 80's where a complete and total Russian retaliatory strike was averted only because a single commander had some rational thinking capacity and realized that what every instrument and warning was telling him was wrong. Russian early warning systems identified sun shining off satellites and other space debris as inbound missiles and a preemptive attack upon the Soviet Union (Russia). He held off announcing the alarm and thus averted a disaster or complete attack from Russia on America. It should be noted and understood that Russia has an all or none strategy whereby they don't launch a one for one response to an attack but would immediately launch a total strike using all of Russia's Nuclear arsenal against our Nation. The though is that the policy would deter any thought by a US commander that they could achieve victory over Russia by taking out most of their capability or communications. We would know that any attack would be met with a total launch of all their capabilities. That is horribly dangerous given that humans do make mistakes.