Air carrier Captain reported a false Terrain EICAS warning at 30;000 ft. during cruise. The Captain maintained level flight and the alert stopped. The Captain indicated that the aircraft was operating in airspace of known GPS jamming.

Narrative

We were just north west of SULOM; in contact with Lahore ATC at FL300. Unexpectedly; the aircraft commanded a terrain escape maneuver; with both aural and visual commands. I exercised emergency authority and we maintained level flight. After about 45 seconds the alert stopped and an TERR (Terrain) EICAS message appeared. The flight continued uneventfully.This flight operates in areas of known GPS interference. More commonly recognized is the area in Turkey over and near the Black Sea (as well as near Syria). Recently; we have seen an increase in this activity in the area of the Pakistan/India FIR (Flight Information Region) boundary also. Normally this is evident in the aircraft by loss of ADSB and TERR Shift messages followed by loss of terrain mapping capability. It is expected and resolves itself upon leaving the area. In rarer instances; the loss of accurate GPS position can cause loss of satellite link and even loss of GPS position updating. Again these normally resolve upon leaving the affected area. Last night was the first time I have had a Terrain warning of any kind. It is worth noting that we did hear another aircraft with Delhi Control; just prior to crossing the FIR boundary that got an alert and did respond; but they were well below us but in the same area. Another factor is that all of the areas where this GPS interreference is present are fairly heavily traveled. Pakistan and India have a relatively small number of FIR crossing points for international flights; for instance; virtually all of the traffic transiting Pakistan to Europe and Eurasia have to file over SULOM. Similarly; with war in Ukraine and Russian airspace restricted; large amounts of traffic route along the southern coast of the Black Sea.My primary concern is the relative inexperience we are seeing in the cockpit. I have flown with crew members who were not fully aware of this problem; and had crew members do things like write up the GPS as inoperative when if fact it wasn't. In and of itself this is not dangerous; but certainly reacting inappropriately to a false terrain escape warning; especially near the maximum operating altitude of the aircraft and in close proximity to other aircraft could be extremely hazardous and lead to loss of aircraft control or midair collision.