President Donald Trump expressed frustration that impeachment seems to be moving forward, and there's nothing he can do to stop it.

The president spoke to reporters Thursday afternoon at Joint Base Andrews, after his acting director of national intelligence testified about his handling of a whistleblower complaint that prompted House Democrats to launch a formal impeachment inquiry.

"What these guys, Democrats, are doing to this country is a disgrace, and it shouldn't be allowed," Trump said. "There should be a way of stopping it -- maybe legally, through the courts. But they're going to tie up this country. We can't talk about gun regulations."