Washington - Five transgender women in the US military are suing President Donald Trump and the Pentagon over Trump's recent announcement he would reinstate a ban on transgender people serving in uniform. In a lawsuit filed in federal court on Wednesday, the five plaintiffs from the Air Force, Coast Guard and the Army said they faced uncertainty about their futures, including whether they would be fired or lose post-military and retirement benefits. In a series of three tweets last month, Trump upended an Obama-era policy of more than a year that allowed transgender troops to serve openly.His announcement came with little or no co-ordination with the Pentagon and landed while Defence Secretary Jim Mattis was on vacation, leaving the astonished department scrambling to come up with a coherent response.The lawsuit was filed against Trump, Mattis and various other senior military officials by the National Centre for Lesbian Rights (NCLR) and GLAAD, a legal advocacy group.'Jane Doe' plaintiffs All the unidentified "Jane Doe" plaintiffs were previously men who have transitioned to being female."Trump's directive to exclude transgender people from military service has created a tidal wave of harms that have already been felt throughout our armed services," NCLR legal director Shannon Minter said."Transgender service members have been blindsided by this shift and are scrambling to deal with what it means for their futures and their families."The lawsuit asserts that reinstating the transgender ban is unconstitutional.The number of transgender troops among America's 1.3 million active duty service members is small, with estimates ranging from between 1 320 and 15 000.On June 30, 2016 then defence secretary Ash Carter said the military could no longer discharge or deny re-enlistment to troops based solely on their gender identity.Pentagon That means transgender troops who were encouraged to come out under one administration now face getting booted under another - a potential legal quagmire for the Pentagon. In the two weeks since Trump's tweets, the White House has still not provided the Pentagon with clear directives on how it should implement a transgender ban, so the current policy remains in place for now. A Pentagon spokesperson said he could not comment on pending litigation.