The policy targets 4,240 service members who may be distressed because their gender identity differs from their sex at birth.

Lower courts had blocked the policy, saying it was not supported by evidence and violated equal protection principles.

By Andrew Chung (Reuters) -One of President Donald Trump's most contentious policies - his attempt to restrict automatic birthright citizenship - arrives at the U.S. Supreme Court this week with an unusual twist: The justices may focus on something else entirely.