a thermonuclear weapon warhead were released. Initial estimates in first few days were between 70 and 160 kilotons and were raised over a week later to range of 250 to over 300 kilotons. Jane's Information Group estimated, based mainly on visual analysis of propaganda pictures, that the bomb might weigh between . Public knowledge The Teller–Ulam design was for many years considered one of the top nuclear secrets, and even today, it is not discussed in any detail by official publications with origins "behind the fence" of classification. The policy of the US Department of Energy (DOE) has always been not to acknowledge when "leaks" occur since doing such would acknowledge the accuracy of the supposed leaked information. Aside from images of the warhead casing but never of the "physics package" itself, most information in the public domain about the design is relegated to a few terse statements and the work of a few individual investigators. Here is a short discussion of the events that led to the formation of the "public" models of the Teller–Ulam design, with some discussions as to their differences and disagreements with those principles outlined above. Early knowledge The general principles of the "classical Super" design were public knowledge even before thermonuclear weapons were first tested. After Truman ordered the crash program to develop the hydrogen bomb in January 1950, the Boston Daily Globe published a cutaway description of a hypothetical hydrogen bomb with the caption Artist's conception of how H-bomb might work using atomic bomb as a mere "trigger" to generate enough heat to set up the H-bomb's "thermonuclear fusion" process. The fact that a large proportion of the yield of a thermonuclear device stems from the fission of a uranium 238 tamper (fission-fusion-fission principle) was revealed when the Castle Bravo test "ran away," producing a much higher yield than originally estimated and creating large amounts of nuclear fallout. DOE statements In 1972, the DOE declassified a statement that "The fact that in thermonuclear (TN) weapons, a fission 'primary' is used to trigger a TN reaction in thermonuclear fuel referred to as a 'secondary'", and in 1979, it added: "The fact that, in thermonuclear weapons, radiation from a fission explosive can be contained and used to transfer energy to compress and ignite a physically separate component containing thermonuclear fuel." To the latter sentence, it specified, "Any elaboration of this statement will be classified." (emphasis