"Seven satellites were destroyed as radiation knocked out their solar arrays or electronics, including the first commercial relay communication satellite ever, Telstar."
Such an explosion today would probably cripple global communications for a month. The device used in this test had a 1.4 Megaton yield, and present speculation paints Israel as the sole, non-NNPT signatory that may possess megaton devices, which is not to imply Israel has any obvious motivation for doing something like this in the near future.
However, as the number non-NNPT signatories grow in number and in yield stockpiled, so does the risk of someone (again) triggering such an explosion intentionally.
Such an explosion today would probably cripple global communications for a month. The device used in this test had a 1.4 Megaton yield, and present speculation paints Israel as the sole, non-NNPT signatory that may possess megaton devices, which is not to imply Israel has any obvious motivation for doing something like this in the near future.
However, as the number non-NNPT signatories grow in number and in yield stockpiled, so does the risk of someone (again) triggering such an explosion intentionally.