Why was the allied bombing of dresden not a war crime (world war two)?

While today considered a war crime, the Allied bombing of Dresden was based on supposedly actionable intelligence to disrupt and destroy key infrastructure points.

Explanation:

Today, most historians agree that the scope of the Dresden firebombings constitute as war crimes. During WWII (13 February, 1940,) the Allies believed that numerous key infrastructure points, namely railways, communications equipment, and supply depots, were based in Dresden. By eliminating them, the Allies believed they could strike a crippling blow to the Nazi’s supply lines. They made efforts to target the locations they were of crucial importance to the Nazis. In reality, their efforts resulted in the unwitting death toll of ~135,000 civilians and the destruction of one of Germany’s most beautiful cities.

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