The former Olympian came out as a transgender woman two years ago, and said earlier this month that she was talking with members of the Trump administration about LGBQ rights issues.
Trump announced his plan to pursue the ban in a series of three tweets.
"After consultation with my Generals and military experts, please be advised that the United States Government will not accept or allow Transgender individuals to serve in any capacity in the U.S. Military," Trump tweeted. "Our military must be focused on decisive and overwhelming victory and cannot be burdened with the tremendous medical costs and disruption that transgender in the military would entail. Thank you."