Classified and Public: B-53 Bomb Yield Declassified

02.11.15 | 2 min read | Text by Steven Aftergood

The explosive yield of the B-53 thermonuclear bomb, once the highest-yield nuclear weapon in the U.S. arsenal, was 9 Megatons. “Effective 20 November, 2014, the Department of Defense and the Department of Energy jointly declassified the fact that the yield of the B53/W53 Y1 was 9 megatons,” according to a notice posted on a DoD website last week.

This is less of a breakthrough in declassification policy than might be supposed, since the 9 Megaton yield for the B-53 bomb has been publicly reported for decades, including on this 1997 web page.

But it seems that this information had not been officially disclosed before. Now that it has been, it can be publicly acknowledged by government employees without penalty and it no longer need be painstakingly redacted from historical documents as they are processed for declassification.

The problem of nuclear weapons information that is both formally classified and readily available to the public has long been a challenge for the Department of Energy.

Last September, DOE updated its longstanding “GEN 16” policy which dictates a “no comment” response to classified information in public settings.

The newly revised no-comment policy “recognizes that it is possible to have incidental contact online” with a classified document and that “merely reading the document online does not constitute a comment.” See Classification Bulletin GEN-16, Revision 2, No Comment Policy on Classified Information in the Open Literature, September 23, 2014.

A DOE training package gives guidance on how to respond, and how not to respond, to public references to information that is classified, in accordance with the GEN-16 policy. The following exchange is offered as an example of what NOT to say:

Joe: “Can you believe there were weapons in X country?” [when that fact is classified]

DOE: “I thought everyone knew that”

Instead, suggested alternative DOE responses are: “I never really thought about it,” or “DOE doesn’t confirm or deny the presence of weapons in most countries.”

Another example of what NOT to say:

Joe: “Is it true you’re holding up publication of Jim’s book on his work in nuclear weapons development because of classification concerns?”

DOE: “It’s taking a long time to review, not just because there is a lot of classified information about thermonuclear weapons, but also because it’s boring.”

One should also not disconfirm the status or validity of published nuclear-related information, DOE advises. Thus, one should not say, “I hope terrorists read that article, because the [nuclear weapon] design was a joke.”

See DOE briefing on Classification Bulletin GEN-16, Revision 2, Classification Training Institute, October 2014.