I would not say that they were racially motivated, but perhaps racially apathetic.

There is that famous poll from 1944 that says that 13% of Americans were in favor of killing off the entire Japanese race. That's certainly not a majority of the people in the United States, but it is a significant figure. Certainly when it came time to intern many Japanese-Americans, members of the Roosevelt administration had no issue doing that.

My point is that when the decision comes for the United States to drop the bombs on Hiroshima and Nagasaki, it's not outside the realm of possibility to think that Truman and company could stomach killing many Japanese people in order to push them into a position of "unconditional surrender". It is quite possible and probable that they considered them racially inferior and so therefore dehumanized them, making the decision easier. Did the Truman Administration want to exterminate the entire race? Certainly not. They wanted to install their own government there, one that was friendly to the United States. And they were, of course, eventually successful.