The Number of Times We Could Blow Up the Earth Is Once Again a Secret

Collectively, Russia, China, the United States and the world's other nuclear-armed countries possess enough fissile material to blow up the planet many times over. Exactly how many times that is, however, became more of a mystery Monday.

At last count, in 2010 , the Pentagon revealed it was the proud owner of 5,113 all-American nuclear warheads. That's down from a high of more than 31,000 in the late 1960s.

How many nukes does the Defense Department have now?

This should have been an uncontroversial question, considering that just three years ago, the Pentagon was more than happy to oblige.

"Increasing the transparency of global nuclear stockpiles is important to non-proliferation efforts," read an unprecedented agency report on the size of the U.S. strategic arsenal.

Non-proliferation experts hoped that the initial revelations would lead to further reports. But a recent Freedom of Information Act request for an updated number has since been summarily rejected . The number of active and inactive warheads in the U.S. strategic arsenal appears to have ducked behind the veil of secrecy once again, thanks to a part of the Atomic Energy Act that lets the government withhold the true size of its nuclear stockpile.

While the Federation of American Scientists—the group that filed the FOIA request—is invoking the act's declassification clause in an attempt to get Washington to talk, for now we're left guessing as to how many thousands of times this could happen: