President Donald Trump has asked the Supreme Court to rule on whether he can bar transgender people from serving in the military - escalating a row which was expected to play out in a series of courts, over many months.

Mr Trump announced in a series of tweets in July 2017 that he wanted to ban transgender people from the armed forces, surprising military leaders and members of Congress.

In March of this year he made an official announcement.

The president said he was “doing the military a great favor” by “coming out and just saying it.”

Federal courts, however, have blocked the Trump administration from enacting the ban.

The Ninth Circuit court heard arguments in October, but is yet to rule, and a Washington DC appeals court is due to hear arguments next month.