TR+G
A Van,
Its a long time since I flew a military aircraft BUT if I recall correctly, in my time, RAF radios had a TR +G function, so we COULD monitor 243 Mhz at ALL times.
Operating close to a sensitive border (such as I did in Germany in my Canberra in the 1960s ) without monitoring a guard frequency does not seem to be a bright idea, regardless of the operational requirements !
...and to avoid exactly this situation we had a "buffer zone" ( 10 miles??) and if we heard a broadcast on 243 that someone was getting close to the EG border we ALL turned west to avoid the situation which occurred in Syria or Turkey ! Worked well for us.