Seriously... the "but but but America did it to Iraq too" bullcrap is outrageous. You'd be hardpressed to find any sensible American that doesn't think the second Iraq war was horrific and embarrassing. There were also many, many Americans who opposed it and that number only grew over time.
This whole justification is really telling. When someone makes it, I almost immediately lose all respect for any sentence or cogent thought that comes after it. It's also a tell as to that person's core values - they're likely a Russian bot, pro-Putin, pro-fascims or bizarrely and ignorantly anti-state with reckless regard.
To those out there making this argument... at least learn from the American people - that was is now looked at shamefully as the Bush admin consciously misled the public for years and years. Don't make the same mistake.
What Putin is essentially threatening to do at Mariupol at this juncture is commit a form of genocide: ultimatums of military tribunal for all remaining residents is likely Gulag or death sentence based on identity, heritage and nationality. It's a crime on many levels and frankly, not up for debate. The indiscriminant targeting that has become common and widely confirmed is appalling.