Over the next six months, the XXI Bomber Command under LeMay firebombed 67 Japanese cities. The firebombing of Tokyo , codenamed Operation Meetinghouse , on March 9–10 killed an estimated 100,000 people and destroyed 16 square miles (41 km 2 ) of the city and 267,000 buildings in a single night. It was the deadliest bombing raid of the war, at a cost of 20 B-29s shot down by flak and fighters.  By May, 75% of bombs dropped were incendiaries designed to burn down Japan's "paper cities". By mid-June, Japan's six largest cities had been devastated.  The end of the fighting on Okinawa that month provided airfields even closer to the Japanese mainland, allowing the bombing campaign to be further escalated. Aircraft flying from Allied aircraft carriers and the Ryukyu Islands also regularly struck targets in Japan during 1945 in preparation for Operation Downfall.  Firebombing switched to smaller cities, with populations ranging from 60,000 to 350,000. According to Yuki Tanaka , the . fire-bombed over a hundred Japanese towns and cities.  These raids were also devastating. 
The Strategic Bombing Survey’s conclusions highlight another important factor in the decision to employ the bombs against Japan: the message such a display would send to Josef Stalin. Uneasy allies in the war against Germany, Russian forces joined the war in Japan in August 1945. Contemporary observers noted that the demonstration of the deadly new weapon’s considerable might had the additional effect of warning Stalin that the . would exercise considerable power in the postwar period. Furthermore, dropping two bombs only days apart had the added benefit of convincing the Russians that the . possessed a formidable supply of the new weapons; when in fact, the . nuclear arsenal was entirely depleted after the two attacks on Japan.
The nuclear age dawned, gravely and with unspeakable carnage, upon the broken and barren horizon of Japan’s devotion to total war. In such a context, I would propose that it is conceivable that our US leaders could, in the framework of just war and via the principle of double effect, arrive at a morally defensible decision to drop the first and second atomic bombs. The expected high number of casualties, not only with the A-bombs but with prior bombing raids, too, were not viewed as the result of indiscriminate bombing. The notion of a general population being viewed as and used as “combatants” arose not from the United States but from the Empire of Japan.