Alternatives to Hiroshima and Nagasaki?

In this thread about the decision to drop the atomic bomb, anonymous asks:

Why didn't they drop a nuke on an unpopulated area and say, 'See that goddamn horror? We'll drop another one on your heads in two days if you don't surrender.'

My post had ended with this quote from Fussell's article about the atomic bomb, which I think is especially relevant to anonymous' question:

The past, which as always did not know the future, acted in ways that ask to be imagined before they are condemned. Or even simplified.

Many of those who are critical of the dropping of the Hiroshima and Nagasaki bombs seem to lack the capacity to understand that those who made the decision were given a certain set of circumstances with which to work. One of those circumstances was a fairly basic one: the US only had two atomic bombs at the time.

Somewhere along the line I had come across this fact, and I wanted to check to see whether my memory was correct. The second article that came up when I Googled "Hiroshima only 2 bombs available" was written by Jamie Glazov, and appeared on August 7, 2001 here, at frontpagemag.com. It contains the answer to anonymous' question, and more. The article sheds much light on the complex dilemmas facing those who were actually making the decision in real time, and what the obstacles were to alternatives such as the one suggested by anonymous.

I am taking the liberty of printing some longish excerpts from this important article by Glazov:

Many critics, however, have insisted that the U.S. could have devised a way to "demonstrate" the awesome power of the bomb to make the Japanese surrender. For instance, it has been argued that the Americans could have dropped the bomb on some built-up area, after giving notice to the inhabitants to evacuate.

No.

A failure under those crucial circumstances could have done enormous, if not fatal, damage to American credibility. There were only two bombs available at the time, and the actual bomb devices were new and scarcely tested. Americans could not ignore the psychological effect on Japanese leaders if the bomb did not work.

To broadcast a "warning" was to risk the operation in other ways. It would have been child's play for the Japanese to intercept an incoming airplane, especially if they knew where and when it was expected.

Truman and his officials agonized over the fact that the Japanese could end such an endeavor altogether by placing American POWs into the "announced" target area. The Japanese had, after all, given the order to kill all POWs once an invasion of the islands began.

In pursuit of their anti-American odyssey, critics have also alleged that a "tactical strike" could have been carried through. In other words, the bomb could have been dropped on a purely military target, an arsenal or a harbor, and without advance notice. They have also theorized that the bomb could have been dropped, without advance warning, over a relatively uninhabited stretch of Japanese territory where the Japanese high command could witness it first hand, and would, therefore, finally accept the futility of their struggle.

There were, even at that time, many suggestions that advocated an explosion at night over Tokyo Bay, which might have served as a satisfactory example. Still another alternative proposed that the bomb could be detonated not on Japan but in some remote corner of the world, and that this would have been enough to scare the Japanese.

First, all of these scenarios imply that the Americans were dealing with a sane Japanese leadership. That was not the case.

Second, no known military target had a wide enough compass to contain the total destructive capacity of the bomb – and to allow it to show what it was capable of doing.

No one could suggest, or even be sure, of a way in which the bomb could be used in so convincing a manner that it would frighten a leadership that worshiped "death before dishonor." The very idea of "demonstrating" the bomb ran counter to its very purpose: to shock the Japanese out of their faith that dying in war was a noble enterprise.

Not even the scientists who made the atomic bombs were fully certain about the destructive potential of the bomb and its radioactive fall-outs. A test in a remote area, therefore, even if successful, could prove useless. It would be done on neutral soil and the Japanese could think it was a fake, accomplished with a massive amount of ordinary TNT. In addition, the Truman administration feared that advance notice of this kind of demonstration would simply give the Japanese too much useful information.

In May 1945, four distinguished physicists who served as advisers to the interim committee met in Los Alamos to consider the proposed "demonstration" theories. They were Arthur H. Compton, Enrico Fermi, Ernest Lawrence and Robert Oppenheimer. After the meeting they concluded: "We can propose no technical demonstration likely to bring an end to the war; we see no acceptable alternative to direct military use."