WASHINGTON — Defense Secretary Jim Mattis kicked President Trump’s proposed ban on transgender people serving in the military down the road, announcing that transgender service members will continue to be allowed to serve pending the results of a study.

In a statement on Tuesday evening, Mr. Mattis said that he was establishing a panel of experts, serving within the Pentagon and the Homeland Security Department, whose task will be to “provide advice and recommendations on the implementation of the president’s direction.”

Mr. Trump announced last month in an abrupt series of tweets that transgender people would no longer be allowed to serve in the military. The Twitter messages took the Pentagon by surprise, and since then, Defense Department officials have been trying to cobble together a policy that takes into account their desire to allow currently serving transgender people to remain, while at the same time following the dictates of a commander in chief who, by most accounts, had not put a lot of study into the ramifications of his instructions.