President Trump argued Sunday that the federal Russia collusion investigation has ruined the lives of the young people who came to Washington to work in his administration.

“Who’s going to give back the young and beautiful lives (and others) that have been devastated and destroyed by the phony Russia Collusion Witch Hunt?” Trump tweeted. “They journeyed down to Washington, D.C., with stars in their eyes and wanting to help our nation...They went back home in tatters!”

Trump appears increasingly frustrated that the investigation by special counsel Robert Mueller has continued for more than a year, putting a cloud over his presidency. The investigation is focusing on whether the 2016 Trump campaign colluded with Russia to influence the outcome of the race.

Trump didn’t mention any specific names regarding whose lives might have been destroyed. However, several people have left the administration amid the investigation, including 29-year-old Hope Hicks, who was a member of the 2016 campaign and ascended to be the White House communications director.