Outgoing Department of Homeland Security Secretary Kirstjen Nielsen said in her resignation letter Sunday that she’s “immensely proud” of her department’s work during her tenure to outpace the nation’s adversaries. “Despite our progress in reforming homeland security for a new age, I have determined that it is the right time for me to step aside,” Nielsen wrote in the letter, which was published by Axios. “I hope that the next Secretary will have the support of Congress and the courts in fixing the laws which have impeded our ability to fully secure America’s borders and which have contributed to discord in our nation’s discourse.” Nielsen, who faced repeated backlash for her the administration’s zero-tolerance policy, will be replaced by Kevin McAleenan, the current U.S. Customs and Border Protection Commissioner. She added that, “I can say with confidence our homeland is safer today than when I joined the Administration.”