"But there were problems. First and foremost, there were only three devices -- one uranium-based ("Little Boy") and two plutonium ("Fat Man"). It would be at least six months before another could be assembled."
Originally posted by Oldexpat:
"We had only two bombs and the next one was a long way off."
Originally posted by ResponseAbility:
..."The US only had two atom bombs at the time. The first one was dropped on Hiroshima, and the Japanese Emperor still commanded the Japanese forces continue to fight. Then we dropped our last atom bomb on Nagasaki. "
Have to disagree a bit with our FR posters, there was a little known third atomic bomb ready to go in August 1945. First as to the contention that after the US dropped the second atomic bomb on Nagasaki, Japan that the US would not have another atomic bomb ready until the end of the year... The TRUTH is that there was a third atomic bomb being readied for a combat drop. Most people that read the common WWII histories do not believe this is the case, however the standard history about 'only two' U.S. atomic bombs in 1945 is just factually incorrect.
The United States actually had three Atomic weapons ready for use near the end of WWII, two of which were dropped on Japan, the third was being readied for a mission by Col. Tibbets' unit - the 509th Composite Group, when Japan surrendered. The USA had two "Fat Man" plutonium Atomic weapons in its inventory at the end of calendar year 1945.
In an August 2002 interview with Studs Terkel published in the British Guardian newspaper, Paul Tibbetts recalled something similar: "Unknown to anybody else--I knew it, but nobody else knew--there was a third one. See, the first bomb went off and they didn't hear anything out of the Japanese for two or three days. The second bomb was dropped and again they were silent for another couple of days. Then I got a phone call from General Curtis LeMay. He said, 'You got another one of those damn things?' I said, 'Yessir.' He said, 'Where is it?' I said, 'Over in Utah.' He said, 'Get it out here. You and your crew are going to fly it.' I said, 'Yessir.' I sent word back and the crew loaded it on an airplane and we headed back to bring it right on out to Trinian and when they got it to California debarkation point, the war was over."
Source: Warbird Forum: The third bomb
Now about those future bombs to be added to the U.S. nuclear weapon inventory...
There WAS a multi-site production line set up to generate plutonium cores for the "Fat Man" model of the US nuclear stockpile. The US had not just invested 2 billion (1943) dollars just to make five atomic bombs in 1945, a production line was built... The only reason that the US did not go into wartime production mode on the 'Fat Man' plutonium cores is that the war ENDED. The "Little Boy" uranium gun-type atomic weapon first dropped on Hiroshima was a one-off model, never produced again. All of the other US atomic weapons were of the plutonium-implosion "Fat Man" model. So the first bomb was tested in the US during July 1945. Two more atomic weapons were dropped on Japan in August 1945. One more atomic bomb was being readied for Tokyo for late August 1945; it was never delivered. The fifth bomb was completed in November, 1945. At the end of calendar year 1945 the US had two "Fat Man" type nuclear weapons in its inventory out of the five produced in 1945, however if Japan had not surrendered the nuclear 'production line' was designed to produce 7 plutonium cored nuclear weapons per month. More than enough to take care of the Nazis and/or the Japs if WWII had lasted into 1946.
"A third bomb was being shipped from New Mexico, target Tokyo, when the war ended. Production was geared to seven per month with an expectation that 50 bombs would be required to assure that an invasion would not be required. Release of radiation from the untested Hiroshima bomb, designed as the original gun-type and made of uranium, was a surprise. The radiation range was expected to be within the blast radius, that is, a lethal dose of radiation would only kill those already dead from concussion. The Alamogordo bomb test and later production were of the more complicated plutonium, yet cleaner, implosion device."
The United States did feel the need to build more nuclear weapons in the immediate aftermath of WWII, since the demobilization of the 12.34 million Armed Forces of WWII had made the post-war US nuclear monopoly the first-line of defense for the United States and its interests. The expense of the $2 Billion Manhattan Project was amortized over the following production of US nuclear weapons from 1945 onwards.
Here are some numbers on the US atomic weapon stockpile from WWII onwards...
Source: Power Point Presentation USC Berkeley - History - 105, Dr. McCray "Early Nuclear Strategy" Slide #9. looks like this PPT link has disappeared...
Source: Complete List of All U.S. Nuclear Weapons The NuclearWeaponsArchive.org
I wouldn’t doubt a third bomb at all. I haven’t come across it in autobiographies of Presidents and probably never will.
I find is amazing that we had so much fissionable material in 1945. How did we get so far ahead of the Germans?
Nonetheless, my point about Truman's decision still stands. At the point in time (late May, as I recall) when the decision to "test, then attack" was made -- as opposed to "test, then demonstrate" -- the expected inventory of reliable weapons was insufficient to even consider the latter.
Interesting, but in the end it does little to change the analysis. Two or three, we still faced the invasion of Japan and the resultant deaths of millions.