He based the decision on ‘tremendous medical costs and disruption’.
He said in a tweet: ‘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.
‘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.’
Around this time last year, the Pentagon agreed it would allow transgender people to serve across the US military.
There are an estimated 250 transgender troops currently serving.
Since October last year, transgender troops have been able to receive medical care and start formally changing their gender identifications in the Pentagon’s personnel system.
But former defense secretary Ash Carter also gave the services until July 1 to develop policies to allow people already identifying as transgender to newly join the military, if they meet physical, medical and other standards, and have been stable in their identified genders for 18 months.