By law, only 25 retired officers can be brought back to serve in any one branch. Trump’s order removes those caps by expanding a state of national emergency declared by President George W. Bush after 9/11, signaling what could be a significant escalation in the 16-year-old global war on terror.

“We anticipate that the Secretary of Defense will delegate the authority to the Secretary of the Air Force to recall up to 1,000 retired pilots for up to three years,” Navy Cdr. Gary Ross, a Pentagon spokesman, said in a statement.

But the executive order itself is not specific to the Air Force, and could conceivably be used in the future to call up more officers and in other branches.