It is apparently widely believed within the US government that those looted explosives are what in many, perhaps most, cases is being used in car bombs and suicide attacks against US troops. That is, according to TPM sources and sources quoted in this evening's Nelson Report, where the story first broke.

One administration official told Nelson, "This is the stuff the bad guys have been using to kill our troops, so you can’t ignore the political implications of this, and you would be correct to suspect that politics, or the fear of politics, played a major role in delaying the release of this information."

As I've noted, the White House and the Pentagon have known for more than a year that this stuff had gone missing. But the White House, according to TPM sources, has known that this story was coming for at least ten days. Again, not just the underlying facts -- that the stuff had been stolen and was being used against American troops (they've known that for more than a year) -- but the fact that this story was going to break in the not too distant future. And they've been hoping it could be pushed back until after the election.

As another administration source told Nelson, "What the hell were WE doing in the year and a half from the time we knew the stuff was gone, is obviously a huge question, and you can imagine why no one [in the Administration] wants to face up to it, certainly not before the election."

UPDATE:
TPM Assignment Desk: a list of questions reporters might do well to get to the bottom of in this looted explosives story.