Here's some reality based writing on the topic. Fred Kaplan at Slate:
I asked retired Lt. Gen. Michael Hayden, former director of the National Security Agency, whether it’s unlawful or even unusual for someone in Rice’s position to ask the NSA to unmask the names of Americans caught up in intercepts. He replied, in an email, “Absolutely lawful. Even somewhat routine.”
And Jennifer Rubin at the Washington Post:He added, “The request to unmask would not be automatically granted. NSA would adjudicate that, although I’m certain a request from the national security adviser would carry great weight.”
Hayden also said, “There are very plausible, legitimate reasons why she would request such information.” Though he didn’t elaborate on what those reasons might have been, the pertinent regulations specify that unmasking might be requested, and allowed, if the names in question are pertinent to foreign intelligence.
When Rice made her request, there were ongoing investigations of Russia’s involvement in the election, of the role Trump advisers might have played in this involvement, and of efforts by some of these advisers to undermine U.S. foreign policy, specifically on sanctions toward Russia.
It’s worth noting that we don’t know—or at least no news story about the incident has reported—whether the NSA granted Rice’s request and gave her the unmasked names. Even if she did, Hayden emphasized in his email, “the identities would be unmasked only for her”—and not for any other official who received the transcript.
“To summarize,” Hayden wrote in his email, “on its face, not even close to a smoking gun.”
The Trump obsession with “unmasking” names is a blatant attempt to distract and obviously irrelevant. It’s not even helpful to Trump’s case. There are many legitimate reasons for unmasking, and nothing suggests requesting information about the identities of those Russia was trying to assist was illegal or improper. Ironically, by focusing on unmasking, the Trump spinners just remind us that there was an extensive, serious investigation underway because of a comprehensive Russian effort to manipulate American voters and because of unprecedented connections between one candidate’s team and Russia. McMullin exclaims: “If you are going to establish a secret channel with a hostile foreign power, you shouldn’t expect to have your name kept secret!”
It’s hardly out of the ordinary for a White House official like Rice, with high security clearances, to request unmasking. In Tuesday’s Washington Post, Glenn Kessler quotes Michael Doran, a former NSC aide under President George W. Bush, as saying, “I did it a couple of times.”
Another former NSC official, who asked not to be named, told me, “There is a well-established, well-used process for requesting that such information be revealed. You have to have a reason beyond simple curiosity that is tied to some legitimate national-security or law-enforcement purpose.” The intelligence agencies, the ex-official added by email, “take this requirement VERY seriously.” Though this ex-official knows nothing about the situation with Rice, he said that, since she was doing transition work with Trump’s team at the time, it would have been “highly relevant to know whether these people were talking with the Russian government as well.”The thing is, though, the confusion is lapped up by dimwitted Trumpkins - I'm sorry, but there is no way of avoiding not calling them out as easily fooled. They are already primed to believe in conspiracy nonsense - on everything from climate change, Obama is a Muslim from Kenya, Hillary being on her death bed, to massive fraudulent votes. They are putty in the small, orange hands of their hero.
Listen, if you were the national security adviser and learned of this extensive Russian campaign of active measures, knew about all sorts of connections between Russia and one campaign, and found out associates of one candidate were picked up in monitored conversations with Russian agents, wouldn’t you demand to know the names of those involved? Any national security adviser who didn’t would be accused of burying his or her head in the sand. Nothing regarding alleged unmasking that we have heard or seen so far bolsters Trump’s “wiretapping” claim or suggests that anyone in the Obama administration did something illegal or wrong, nor does it tell us who revealed that Flynn was one of the people picked up in surveillance of Russians. What it does confirm is that there was so much evidence of a Russian disinformation scheme and of questionable connections between Trump associates and Russians that it warranted a substantial intelligence investigation.
The Trump spin squad appears so desperate to create confusion — Trump now reverts to airing old campaign canards about Hillary Clinton — that it has confused itself about what is helpful and what is not.
And the Republican Party as a whole has to take the blame for this terrible situation.
Update: The Vox explainer on this is very good, too.