Well, of course.
But, two questions:
(1) What if a lot of the civilians (or, say, all of the civilians age 7 and over) are enrolled in some sort of military project, whether it's training for street-to-street combat, constructing booby-traps, making or assembling armaments in home workshops: that is, if the civilians have been blended with the military so that it is impossible to distinguish one from the other? Can they be directly targeted?
(2) What if, as long as the war goes on, the enemy's killing about 200,000 civilians per month in the areas occupied by their military? (We're talking about deliberate starvation, slave-labor camps where people die of disease and exhaustion, and people just plain being shot in the head.) If you can end the war in a matter of days by hitting military targets but causing 150,000 deaths in collateral damge (not intended but foreseen --- and you gave them a warning), is that OK proportionality-wise?
Ears perked.
1) Yes. If they cannot be distinguished, they cannot be distinguished.
2) Yes.