Trump had tweeted, “I don’t believe the four Congresswomen are capable of loving our Country,” saying that they should go back to their own countries. All four were US citizens, with three having been born in the US. After lying about having prepared talking points to attack the Congresswomen, he then demanded an apology from Ilhan-Omar of Minnesota. She had remarked about Republican Congressmen only supporting Israel because they were paid to do so from Israeli lobby groups. When she walked back the remark, Trump called her apology “lame.”

The New York Times – Trump Tells Congresswomen to ‘Go Back’ to the Countries They Came From
Associated Press – Trump calls Rep. Omar apology about Israel remark ‘lame’
Independent – Trump demands congresswomen he subjected to racist tweets apologise to US and Israel