In a blow to Trump, AG Barr's investigation into Flynn's 'unmasking' ended without criminal charges or a public report

A Justice Department investigation into whether Obama-era officials improperly "unmasked" former national security adviser Michael Flynn's name in US intelligence reports has ended with no charges and no public report, The Washington Post reported.

The development is a massive blow to President Donald Trump, who has argued for months that Obama administration officials targeted Flynn as part of the Russia investigation in an effort to undermine Trump before he took office.

"Unmasking" refers to the practice of revealing the identity of a US person whose name is incidentally collected in intelligence reports monitoring the communications of foreign agents.

Attorney General William Barr asked John Bash, the US attorney for the Western District of Texas, to look into the matter as part of an investigation into the origins of the Russia probe being conducted by John Durham, the US attorney for the District of Connecticut.

Bash resigned from the Justice Department last week, and according to The Post, no criminal charges have been brought as a result of the "unmasking" investigation, and there will be no public report. Sources told the outlet that even if the report were made public, it would "likely disappoint" conservatives who have claimed that Flynn and Trump were targeted as part of a vast political conspiracy.

The US intelligence community surveils hundreds of thousands of foreign targets per year, and unmasking is a routine and legal tool officials use to make more sense of the communications they're monitoring. The intelligence community gets thousands of unmasking requests a year.

But Trump and his allies have accused Obama administration officials of illegally unmasking Flynn's name in intelligence reports in 2016 and 2017 monitoring the communications of Sergey Kislyak, then Russia's ambassador to the US.

The conspiracy theory picked up steam in May when Richard Grenell, then the acting director of national intelligence, declassified a list of Obama administration officials who made unmasking requests that included Flynn's name between November 30, 2016, and January 12, 2017. Former Vice President Joe Biden, who is now the Democratic presidential nominee, was among the names on the list.

Trump and his allies seized on the development and said it showed that Biden and others improperly unmasked the former national security advisor's identity.

But a Washington Post report earlier in May debunked that allegation when it revealed that Flynn's name was never "masked" in the first place.

Moreover, the list documented unmasking requests made through the National Security Agency, while transcripts documenting Flynn's conversations with Kislyak were an FBI product, meaning the names on the declassified list Grenell released are unrelated to Flynn's conversations with Kislyak.

Tuesday's report from The Post will likely further inflame tensions between Trump and Barr, particularly following earlier reports that Barr will not be able to deliver a public report on the findings of Durham's investigation before the general election.

Trump has long said that the Durham probe will yield damning evidence of a broad conspiracy against him, but such evidence hasn't yet materialized.

The president unleashed his anger on Barr last week, telling Fox News' Maria Bartiromo, "To be honest, Bill Barr is going to go down as either the greatest attorney general in the history of the country or he's going to go down as, you know, a very sad situation."