"Signals intelligence" refers to any electronic transmission plucked from the air by a spy satellite or other device. Cell phone conversations between suspected terrorist operatives, for example, are recorded, transcribed, and disseminated throughout the IC. Reports often contain brief, vague, but potentially juicy nuggets, along the lines of "Known suspected terrorist A in Islamabad called known suspected terrorist B to discuss the plot in America."

In this example, it's a "SIGINT fact" that the suspected operatives had this conversation, nothing more. The conversation's contents regarding the existence of "a plot in America" are not confirmed. These types of reports arrive at a clip of hundreds per week, yet few are ever linked to verified operations for any number of reasons -- human beings lie, brag, exaggerate, and speak in code all the time. A handful turn out to be true, of course, but the only way to verify the existence of "a plot in America" is to task intelligence assets to collect more about the very specific operatives, sources, and allegations in question.

Reid and House Minority Leader Nancy Pelosi (D-CA) have been careful to stand behind only the occurrence of a conversation in which Reid discussed Romney's tax avoidance, rather than the charge's validity. Reid defended himself saying, "I have had a number of people tell me that," and he clearly states in the original Huffington Post interview that he's "not certain" the allegation is true. Pelosi rushed to his aid saying, "Harry Reid made a statement that is true. Somebody told him. It's a fact." "It" refers to the existence of the conversation, not its contents. Reid and Pelosi are asserting SIGINT fact here, and are on rock solid ground.

Kessler misses this crucial distinction. Worse, he relies on two outside experts' opinions to conclude it's "highly improbable" Romney avoided the taxman for a decade. Yet highly improbable, highly important events do happen. Reid's description of his source and Romney's known proclivity to pay relatively low taxes should be enough circumstantial evidence for Kessler investigate the specifics of the case further.

It would be far more credible had Kessler tracked down Reid's source, or attempted to interview those with direct knowledge of the contents of Romney's returns. Lacking information to "definitively prove Reid incorrect," as he acknowledges, Kessler should have graded the substance of Reid's claim on the Fact Checker scale as "withholding judgement." That's how I would have evaluated the "plot in America" example in an IC report.

Was Harry Reid politically manipulative? Sure. But on narrow merits of Reid's assertion, he's absolutely right.