You can't detonate an old Soviet nuke from the 1970's. The whole concept of long-missing "suitcase" nukes being hidden away to be used at some point in the future by rogue terrorists is fundamentally (religious pun intended) flawed.Let me put this into layman's terms.
For a nuke to detonate rather than "fizzle," you've got to have a precisely shaped fissionable outer shell or globe and a precisely shaped core. Most nuke designs, especially the *smaller* (read: suitcase sized) ones also require a nuclear "trigger" (which is made up of a substance that emits large quantities of neutrons at high speeds...a fact of science that simultaneously causes the trigger to decay rapidly with a very short "half life").
So for the radioactive components of a nuke, you've got to have precise shapes, and you've got to detonate the device *before* the radioactive elements decay past a certain point. The "trigger" decays the fastest, and it is reasonable to say that most atomic triggers are going to be worthless after 120 days. The core typically decays much slower, and after some number of years will have introduced numerous atomic impurities into itself, and its remaining fissionable material will gradually cease to be over the "critical mass" threshold. The globe/shell typically decays the slowest of all, but even it will have impurities being introduced into itself over the years, impurities that *will* increase the likelihood of getting a "fizzle" rather than a boom.
But wait, there's more!
These radioactive elements wreck havoc upon the electronic components used to detonate the nuclear bomb. Every day that the wiring and circuit components are exposed to this radiation reduces the likelihood of the electronics working as designed. Ditto for the effects of long-term radiation on the convention explosive that are used to initiate the nuclear chain reactions.
So for these basic reasons and many others, nuclear warheads/bombs require an enormous amount of constant maintenance.
Nukes are *NOT* like old WW2 bombs that shrimpers pull up from the sea in their nets every now and again. You don't just ignore a nuke for decades and then think that it will go BOOM!
After 4 months without maintenance, you've got about a 50-50 chance of a fizzle instead of a BOOM.
Each day after that dramatically reduces the chances of the device working as designed. Even rust or normal metallic corrosion will greatly reduce the chances of such an atomic device being anything more than a dirty bomb.
And just for the record: Uranium and Plutonium *are* metals. They are also very brittle, another factor to consider.
So anyone running around claiming that they've got old "suitcase" nukes from the Soviet Union (deceased since 1989) is either patently uneducated on atomic weapons *OR* simply bluffing.
Even if they knew the codes to activate the device, if it is more than 4 months out of maintenance it will probably just fizzle and scare the crap out of every news anchor in NYC.
And this isn't the sort of maintenance that can be performed inside someone's garage, either.
Here's another thought: the terrorists didn't brag about 9/11 *prior* to 9/11.
Those who know, don't talk. Those who talk, don't know.
Your mileage may vary.