Their anger is understandable, but Republicans must stop pushing for more information on the sources behind the so-called Trump dossier.

That dossier on allegations of links between President Trump and Russia was compiled by former British intelligence officer Christopher Steele.

On Tuesday, however, we gained the clearest public evidence yet as to why the dossier sources must remain secret. The evidence came when Sen. Dianne Feinstein, D-Calif., released a transcript of August testimony by Fusion GPS founder Glenn Simpson to the Senate Judiciary Committee. Responsible for hiring Steele, two elements of Simpson's testimony stand out.

First, the claim by Simpson's attorney, Joshua Levy, that one of Steele's sources has already been killed as a result of the dossier's publication.



Why is this relevant?

Well, as I noted in August, a significant number of active and former Russian government officials died in mysterious circumstances between November 2016 and February 2017.

Second, Levy's ardent contention that he could not release the identity of Steele's sources.



This is relevant in the context of my December contention that the reason the FBI has been reluctant to provide more information on the Trump dossier is that to do so would endanger intelligence assets operated by a foreign intelligence service. As FBI Director Christopher Wray put it then, "We are dealing with very, very dicey questions of sources and methods. Which is the lifeblood of foreign intelligence and for our liaison relationships with foreign partners."

Considering Wray's comments, Tuesday's transcript release and the fact that Steele was a top Russia-focus production officer for Britain's CIA equivalent, the Secret Intelligence Service, it doesn't take a genius to figure out what's going on here. Put simply, publication of more information on the Trump dossier would risk the lives of individuals who may be active intelligence assets of the British government.

Seeing as Britain is a highly capable intelligence partner of the United States and all across the world, and that Russia is one of our foremost adversaries, it is of the absolute utmost importance that Steele's sources be protected.