In a radio interview with conservative host Hugh Hewitt Tuesday, President Trump lamented the unmasking of Michael Flynn, who pleaded guilty to lying about conversations with Russian government officials, wondering if he himself was unmasked, inadvertently admitting that he had direct conversations with Russian officials.

From the transcript on Hewitt’s website:

HH: Well, I always feel, I like Chuck. Chuck knows, he’d probably talk sports with you longer than me. But I want to go back to Rice. She was one of the unmaskers of Michael Flynn. Will that be an issue if she’s the vice presidential selection?

 

DJT: 100%. Look, not only, I mean literally not only that, we’re talking about unmasking, yes. That was a big deal. Horrible deal where they unmasked him so many times. I think he’s got to have the record for unmasking. Maybe I do, you know, because we’re still looking how many times did they unmask me. Let’s find that out, too, because look, they were spying on our campaign. They were using him and others, and they were spying on my campaign. So was I unmasked? So far, they haven’t said, but let’s see what happens.

Unmasking is the legal release of an American’s identity when someone is involved in an electronic communication with a foreign national.  The identification is done only at the request of authorized federal officials involved in national security or law enforcement duties. 

Michael Flynn was unmasked because he was involved in conversations with Russian diplomats that undermined US foreign policy under President Obama.

Trump could only be unmasked if he had direct communications with foreign nationals while he was a private citizen.  Trump wondering if he was unmasked is an implicit admission that he did, in fact, have such conversations even through he denied such contact throughout the 2016 campaign.