If they are jamming the GPS of your missiles, how are you going to ‘send a missile there’ ?
It is called the “Home on Jam” option
We designed the GPS antennas on the Excaliber and ERGM projectiles to do that over 30 years ago.
Not every missile needs GPS. A jammer is putting out a strong EMR field, in order to cover/mask actual GPS signals. We have stuff that specifically goes for anything outputting tons of EMR. GPS and/or inertial systems get it in the vicinity, and the EMR seeker directs from there. The jamming antenna is essentially a big neon sign saying ‘come here!’.