Air carrier Captain reported GPS jamming on approach to POS.

Narrative

This report is to inform about GPS jamming incident near POS airport Operating Aircraft X ZZZ-POS. I had called the dispatcher for a briefing before the flight as this was my first flight into POS. Dispatcher mentioned there was nothing out of the ordinary except for 2 threats that was GPS jamming in the vicinity of SVZM FIR and increased military traffic near SVZM FIR as well. Everything else from the flight plan was pretty straightforward.The takeoff and cruise portion of the flight was uneventful. During our descent briefing into POS we started off with the threats and briefed the threats mentioned by dispatch about the military traffic and mitigation strategy of maintaining traffic watch and staying vigilant and pay special attention to 121.5 frequency and mitigation strategy for the GPS jamming we had looked through the non-normal procedure and briefed the conditions from the QRH so it would not catch us off guard during a high workload situation at the end of a long night flight. Me and my FO felt comfortable and prepared as we started our descent into POS.As we descended out of 17000ft approximately we had GPS R invalid scratchpad message show up intermittently. As we descended below 7000ft we had GPS L invalid scratchpad message show up. Upon checking the NAV STATUS page both the GPS were intermittent throughout the descent up until landing. We also had a TERR POS flag on the ND (Navigation Display) which we expected as we briefed earlier. As both IRS's (Inertial Reference System) were operating and we were in VMC all the way and the runway was in sight we executed a normal ILS approach to a landing to runway 10. After landing all the GPS were back to normal and the TERR POS flag on the ND went away. I reported the issue to dispatch.