At the beginning no challenge at all, as there are no bombs dropping, then a middle section where you have to dodge a bit, and at the end they are just carpet bombing you so you have no chance anyway. Getting harder would be ok, but not such dramatic steps.
the level when the soldiers could be saved was also not constant, or didnt seem to be anyway. SOmetimes I could rescue them when their parachute was in the water, other times they died as soon as the soldier touched the drink.