Decimating populations in that way is definitely committing war crimes.
And it isn't true that Western armies didn't act that way after WWII. The Dutch did it in Indonesia, the French in Algeria, the US in Vietnam ( wrt the last: Asia Times on line publish a review of a book about that war that describes exactly that. I referred to it in the History thread. ) The Falluja occupation was also conducted in that way after four mercenaries were killed near the city.
Sorry, I do not think so.
First, the Fulejah campaign was not conducted in that manner at all. IMHO, the US should have encircled the City and given a 96 hour deadline for all inhabatants to leave, and for the fighters to surrender or the US would simply have bombed the place and leave no brick standing. We had the power and the ability to do that. If the terrorists would not let people leave, the blood is on their hands. If the people willingly chose to stay, then it on them.
But we did not do that. First we tried to go in too lightly and were held up and had to back out and regroup and go in with larger numbers and more force later...and then it was a bloody, drawn out, house to house urban war that played to the enemy's strengths. Many Americans were killed and a whole lot more injured. We could have and, IMHO, should have, avoided all of that and warned the people to come out, and then leveled the place as an example.
There was no carpet bombing of populations centers in Vietnam. There were, statictically, relativelty few on the field examples of retaliation and retribution that were not ordered or the policy of the command. When we did bomb the North relentlessly...albeit not the population centers, but all of their factories and harbors, and military sites of all kinds, North Vietnam came to the negotiating table and a a very decent cease fire and peace was established for the South. At that point the VC had almost ceased to exiost as any fighting unit (1972), and the US began to a rapid and large draw down. Then, two years later the North violated that agreement and invaded the South...and the US chose to continue withdrawing and the South was defeated.
If a population is actively and willfully involved in aiding, abetting and supporting a fighting force arrayed against you, then halting that abetting, supporting and aiding becomes a military initiative.
The outcomes, when conducted appropriately, and when showing that same poplulation, after its defeat, that your interest is not taking their land or decimating them personally, is clear. Look at the people the US and its allies defeated in World war II and what has become of them. The US poured trillions of dollars of aid and support into those nations after the war, and then more trillions in trade since...and they are among our strongest allies now, and free and prosperous free nations who themselves now are very well armed.
OTOH, when we have not fought wars to win in this manner, the outcomes over the decades is desidedly less positive, IMHO, to all involved.
As General Sherman noted, "War is hell. Best to end it quickly," and decisively.
Now, if a nation takes the land and then slaughters the inhabitants after winning te war, then that is something altogether different and is genocide and is what we fight against, and put down...and punish.