Pat Flannery wrote:

You stick a small, non-nuclear EMP warhead on it (we have these for
cruise missiles) get it within a mile or so of the target satellite on a
direct ascent trajectory, and set it off; for all your opponent knows
his satellite just suffered a electrical malfunction.

That is assuming said opponent's satellite does not employ design
techniques validated by opponent's equivalent of "Huron King" --

http://nuclearweaponarchive.org/Usa/Tests/Nts.html