RIA News gives a fragment of the text of the very document that was signed by Trump:
I will instruct the Minister of Defense and the Minister of Homeland Security, which is responsible for the Coast Guard, to return to a long-standing policy on transgender persons in military service for a long time until June 2016.
The document states that the ban will be in effect until there are objective grounds for considering the service of transgender people in the troops not to cause material or other damage to government departments. In particular, it is said that at the moment the service of transgender people in the US Army is more expensive financially, and also leads to a mismatch in military units. No specific examples are given.
According to Trump, the leadership of law enforcement agencies can independently make recommendations regarding this issue.
There are no official data on the number of transgender people in the American army. According to American media, their number - up to 5-6 thousands of people.