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Donald Trump Jr. has a very clear picture of who's behind that anonymous New York Times op-ed -- and it ain't no "senior official" in the Trump administration.

We got the President's son heading into Vaucluse Thursday in NYC with his GF, Kimberly Guilfoyle, and when we brought up the NYT piece -- about White House staffers allegedly working against 45 -- junior unloaded.

Don didn't name names, but he made it clear he's not buying the Times' report that it was penned by a "senior Trump administration official." He's convinced it's the other end of the ladder.

In Opinion



In an anonymous Op-Ed, a senior Trump administration official says he and others are working ​to frustrate the president’s “misguided impulses.” https://t.co/qW1IoM3AYY pic.twitter.com/rCHnQfcRjG @nytimes

We broke the story ... Trump's camp wants the Secret Service to launch an investigation to find the culprit.