Donuel

Tritium is only used in fusion devices. It has a short enough half-life that there is a need to make more now, just to maintain existing stocks.
Uranium and plutonium, however, have halflives measured in thousands of years- so a few decades would not make much difference. The explosive used to set it off might decay- but as is seen in Iraq, the stockpiles from 15 years ago seem to be working just fine.