Trump said of the Democratic reaction to his 2018 State of the Union address,

Even on positive news, really positive news like that, they were like death. and Un-American. Un-American. Somebody said ‘treasonous.’ I mean, yeah, I guess. Why not? Can we call that treason? Why not. They certainly didn’t seem to love our country very much.

USA Today – Trump blasts ‘treasonous’ Democrats for not applauding at his State of the Union address
Time – President Trump Said Democrats Who Didn’t Clap at the State of the Union Were ‘Treasonous’
NPR – Trump: Democrats ‘Un-American,’ ‘Treasonous’ During State Of The Union