Did Rod Rosenstein cave to pressure yesterday — or did he just pre-empt it? After reports in the New York Times and the Washington Post that the FBI had an intelligence source in Donald Trump’s presidential campaign, Trump himself announced that he would order the Department of Justice to conduct an investigation of the FBI’s potential politicization:

https://twitter.com/realDonaldTrump/status/998256454590193665

This drew sharp opposition from some quarters, most notably from former CIA director John Brennan:

Senator McConnell & Speaker Ryan: If Mr. Trump continues along this disastrous path, you will bear major responsibility for the harm done to our democracy. You do a great disservice to our Nation & the Republican Party if you continue to enable Mr. Trump’s self-serving actions. https://t.co/uAhgL6wfIC

— John O. Brennan (@JohnBrennan) May 20, 2018

It’s not clear what steps Brennan would have in mind for either Paul Ryan or Mitch McConnell. The president has the authority to direct the Department of Justice to open investigations, since the DoJ operates under executive authority. Congress has little authority over law-enforcement operations except for an oversight role. Impeachment is reserved for abuses of power, which might come into play if a president ordered the closing of an investigation, but Trump’s demand falls clearly within his constitutional authority.

Besides, there has been enough leaked out to justify at least a review. At least according to the reports in the NYT and the Washington Post, the FBI’s “source” is someone who has long worked with both the FBI and CIA as an intel source/operative, perhaps all the way back to the Jimmy Carter era. [His name is now widely known but not yet officially confirmed.] How exactly did this professor end up in the Trump campaign anyway? If Brennan et al didn’t want this source burned, wouldn’t they have told him to stay out of the campaign? There are a lot of curiosities involved here that don’t necessarily add up to a concerted effort to spy on a political opponent, but that conclusion isn’t outside the realm of possibility either.

Despite complaints from Brennan and others, Deputy Attorney General Rod Rosenstein announced almost immediately that the DoJ would open a probe into any “impropriety” in working with any informants within the Trump campaign. The DoJ made a more formal announcement this morning:

“The Department has asked the Inspector General to expand the ongoing review of the FISA application process to include determining whether there was any impropriety or political motivation in how the FBI conducted its counterintelligence investigation of persons suspected of involvement with the Russian agents who interfered in the 2016 presidential election,” Department of Justice spokeswoman Sarah Isgur Flores said in a statement.

“As always, the Inspector General will consult with the appropriate U.S. Attorney if there is any evidence of potential criminal conduct,” she added.

Deputy Attorney General Rod Rosenstein, who has oversight over special counsel Robert Mueller’s investigation into Russian interference in the 2016 race, added that “if anyone did infiltrate or surveil participants in a presidential campaign for inappropriate purposes, we need to know about it and take appropriate action.”

The timing and the direction of this assignment are both meaningful. Rosenstein handed the probe off to the IG before Trump’s formal order arrived, CBS’ Paula Reid reported this morning:

After Pres. Trump demanded the DOJ look into whether FBI "infiltrated" campaign, "Deputy AG Rod Rosenstein didn't wait for a direct order before handing this issue off to the Office of the Inspector General," CBS News' Paula Reid reports https://t.co/a8OMOcLJhu pic.twitter.com/dIyIAuYU2a

— CBS News (@CBSNews) May 21, 2018

Rosenstein pre-empted Trump’s directive by handing this off to the IG, who’s already looking into other potential problems with the FBI’s handling of the Russia investigation. It’s a smart move by Rosenstein, as it doesn’t actually start a new investigation, but merely expands the existing probe — and in a direction it likely would have had to go organically without Trump’s direction. If this informant triggered the Russia probe and all of the questionable activity surrounding it, the IG would have eventually had to address how the informant came to be in the campaign, especially given his track record as a source for the FBI and CIA going back decades. If anything, Trump might have made it momentarily tougher for the IG to get that part of the job done by making it such a public issue.

Plus, IG Michael Horowitz appears to be the right office for this task. He has already made a criminal referral on Andrew McCabe for his role in leaking and then misleading investigators about the Hillary Clinton probe, so he’s independent enough from the FBI’s leadership to get to the bottom of issues. Horowitz has held these investigations close to the vest too, which means leaks shouldn’t be an issue. The results of the larger investigation may take longer than Trump wants, but the results are likely to be thorough, reliable, and politically bulletproof. The only question will be whether Trump will be patient enough to allow Horowitz to do the job … and whether the rest of us will be, too.