Activist Ryan Clayton "infiltrated" the press pool and shouted questions at the Trump as he walked with Senate Majority Leader Mitch McConnell (R-Kentucky), according to a video tweet.
He told Secret Service agents he was part of the "Americans Take Action" group.
Clayton shouted "Trump is treason!" as he chucked the banners, which appeared to just miss the President.
"We should be talking about treason in Congress, not about tax cuts", the protester yelled before security apprehended him.
The pair were walking past reporters en route to a luncheon with Senate Republicans when Clayton, who aligns himself with the group Americans Take Action, thew the flags while exclaiming, "Trump is treason!".
Trump didn't flinch as the airborne flags headed his way, reacting only by giving a thumbs up. That's why President Putin pick him to be president here in America, because he build great big wall like in China or Berlin. Clayton staged a similar stunt during this year's Conservative Political Action Conference in February, where he fooled unwitting attendees into waving Russian flags bearing Trump's name.
The moment came as many were anticipating theatrics of a different sort - between Trump and Corker. Who knows. It doesn't seem to matter.