Kirstjen Michele Nielsen (born May 14, 1972) is an American politician and attorney who is a former United States secretary of homeland security. She is a former principal White House deputy chief of staff to President Donald Trump and was chief of staff to John F. Kelly during his tenure as secretary of homeland security.
Nielsen was confirmed as secretary of homeland security on December 5, 2017. Following her appointment, Nielsen implemented the controversial Trump administration family separation policy. She resigned in April 2019.
Kirstjen Michele Nielsen was born on May 14, 1972, in Colorado Springs, Colorado, to Phyllis Michele Nielsen and James McHenry Nielsen, both United States Army physicians. Nielsen's father is of Danish ancestry while her mother is of German descent. The oldest of three children, Nielsen has a sister, Ashley, and a brother, Fletcher. Following Nielsen's birth, the family relocated from Colorado Springs to Clearwater, Florida.