B757-200 Captain reported GPS jamming on approach to the airport and requested vectors from ATC. The flight crew expressed concern that vectors from ATC were placing them in unsafe proximity to terrain.

Narrative

We had flown to ZZZ the previous day when we experienced an ATC Fail EICAS message and we quickly figured out from ATC that the military was jamming GPS throughout the area. My FO (First Officer) and I discussed our not being able to fly the RNAV GPS arrival. We asked for vectors; which we received and landed uneventfully. The next day the same thing happened and we asked for vectors again on the arrival to ZZZ. We were vectored further north and terrain became a concern; looking at the terrain display and out the windshield. My FO called Approach to confirm we were safe where we were. Finally; I asked the FO to tell Approach we wanted a left turn to the south for more spacing on the terrain.I was descending in flight level change and we were becoming more concerned about the terrain that I failed to slow to 250 kt. below 10;000 ft. I quickly corrected around 9;400 ft. and immediately slowed to 250 or below. Before we got a left turn; the controller informed us the MVA was 9;000 ft. and he cleared us to 8;000 ft. At that point we became very uncomfortable. Also; the controller told us we could climb back to 9;000 ft. if we wanted to; which I didn't feel necessary since we got a left turn. The controller never specifically told us to climb and maintain 9;000 ft. He asked us if we had climbed to 9;000 ft. after we had turned; which I found odd. He then informed us that 'now you're in the way of some other traffic.' We landed uneventfully and never got a GPWS terrain caution.I believe the jamming of the GPS signals set this in motion; I don't know if it was because of [the event] or not. We were being proactive as my FO and I briefed what we were going to do as far as getting vectors is concerned before we ever left our departing city; and again 250 miles from ZZZ.