Defense Secretary Jim Mattis said Tuesday night that the Pentagon's current policy on transgender troops "will remain in place" while President Trump's directive banning transgender people from joining the military undergoes an expert study.

The move by Mattis allows transgender people to continue serving openly in the military while the Pentagon considers whether to discharge them in light of Trump's order.

In a statement, Mattis said that Trump's directive would be reviewed by a panel of experts from the Departments of Defense and Homeland Security.

"Once the panel reports its recommendations and following my consultation with the secretary of Homeland Security, I will provide my advice to the president concerning implementation of his policy direction," Mattis said.

Trump formally directed the Pentagon to implement the ban on transgender individuals joining the military last week, which he first announced in a July 26 tweet. Trump also gave the Pentagon the authority to decide the future of openly transgender people already serving.

"The implementation plan will address accessions of transgender individuals and transgender individuals currently serving in the United States military," Mattis said. "Our focus must always be on what is best for the military's combat effectiveness leading to victory on the battlefield."

Transgender people have been able to serve openly in the military since last year, when then-Secretary of Defense Ash Carter lifted a prior ban during the Obama administration.