After hearing arguments from scientists and military officers over the possible use of nuclear weapons against Japan (though some recommended using them as demonstrations in unpopulated areas, most recommended using them against built up targets, a euphemistic term for populated cities), Truman ordered the use of the weapons on Japanese cities, hoping it would send a strong message that would end in the capitulation of the Japanese leadership, and avoid a lengthy invasion of the islands. Truman and his Secretary of State James F. Byrnes were also intent on ending the Pacific war before the Soviets could enter it, given that Roosevelt had promised Stalin control of Manchuria if he joined the invasion. On May 10–11, 1945, the Target Committee at Los Alamos, led by Oppenheimer, recommended Kyoto, Hiroshima, Yokohama, and Kokura as possible targets. Concerns about Kyoto's cultural heritage led to it being replaced by Nagasaki. In late July and early August 1945 a series of leaflets were dropped over several Japanese cities warning them of an imminent destructive attack (though not mentioning nuclear bombs). Evidence suggests that these leaflets were never dropped over Hiroshima and Nagasaki, or were dropped too late.