you cant really keep them under control, this is a genie you cannot put back in the bottle.

one of the core reasons why they are " controlled" is because no single nation has a monopoly of them and said nations are adversaries, as a result of this knowledge all sides went to very extreme measures to ensure they can always retaliate against a nuclear strike as part of their doctrine.

this knowledge resulted in one of 2 principles that still hold ot this day that stop nuclear war : M.A.D.(mutually assured destruction) that dictates that unless you are fully capable of negating your enemy's ability to retalitate launching a nuclear strike is always gonna result in a phyrric victory where nobody wins.

the other principle is the knowledge that a nuclear conflict will stall the global economy meaning none of the interested parties make money anymore(if said parties discovered a means ot turn a nuclear exchange into a profitable thing, then we should all be very scared), this means there is a vested interest in preserving the status quo(ie: this is one of the suspected reasons the current conflict in easterm europe will likely not reach the nuclear phase.)