Banning transgender people from serving in the American military would be “doing the military a great favour,” Donald Trump has said - a statement undercut by resistance to the proposal from current and former servicemembers.

Mr Trump was seeking to defend his controversial prohibition on transgender troops, which he announced on Twitter to the reported surprise of military officials. After claiming to enjoy “great support from that community,” an apparent reference to transgender Americans, Mr Trump framed the proposal as a gift to the armed forces.

“As you know, it’s been a very complicated issue for the military, it’s been a very confusing issue for the military, and I think I’m doing the military a great favour,” Mr Trump said.

In the short term, uncertainty seems to have outweighed gratitude in the official military response. General Joseph Dunford, chairman of the Joint Chiefs of Staff, responded to Mr Trump's initial announcement by saying military policy toward transgender troops would not change until Mr Trump issued a directive through formal channels.

“In the meantime, we will continue to treat all of our personnel with respect,” Mr Dunford wrote in a message to military officials.

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And Mr Trump's claim of helping the military solve an intractable problem contradicts the message from dozens of former admirals and generals, who said a transgender troop ban would “cause significant disruption.”

Mr Trump's tweets have also led five active duty transgender service members to sue the US President and members of his administration, asserting that any ban on transgender military service is unconstitutional.

In a complaint filed in Washington DC federal court, the members say that Mr Trump's directive has already unsettled and destabilised their “reasonable expectation of continued service”. They added that the White House has turned the President's tweets into “official guidance, approved by the White House counsel's office, to be communicated to the Department of Defense.”