In a statement Thursday, Pentagon spokesman Sean Parnell affirmed that Hegseth “will be addressing his senior military leaders early next week,” but he offered no additional details. Parnell, a senior adviser to the defense secretary, voiced no concerns about The Washington Post reporting on the meeting, scheduled for Tuesday in Quantico, Virginia.

There are about 800 generals and admirals spread across the United States and dozens of other countries and time zones. Hegseth’s order, people familiar with the matter said, applies to all senior officers with the rank of brigadier general or above, or their Navy equivalent, serving in command positions and their top enlisted advisers. Typically, these officers each oversee hundreds or thousands of rank-and-file troops.

Top commanders in conflict zones and senior military leaders stationed throughout Europe, the Middle East and the Asia-Pacific region are among those expected to attend Hegseth’s meeting, said people familiar with the matter, who spoke on the condition of anonymity as they were not authorized to publicly discuss the issue. The order does not apply to top military officers who hold staff positions.

None of the people who spoke with The Post could recall a defense secretary ever ordering so many of the military’s generals and admirals to assemble like this. Several said it raised security concerns.

“People are very concerned. They have no idea what it means,” one person said.

Two others expressed frustration that even many commanders stationed overseas will be required to attend. One said, this is “not how this is done.”

“You don’t call GOFOs leading their people and the global force into an auditorium outside D.C. and not tell them why/what the topic or agenda is,” this person said, using an abbreviation for general officer or flag officer.

“Are we taking every general and flag officer out of the Pacific right now?” one U.S. official said. “All of it is weird.”

The orders come as Hegseth has unilaterally directed massive recent changes at the Pentagon — including directing that the number of general officers be reduced by 20 percent, firing senior leaders without cause and a high-profile new order to rebrand the Defense Department as the Department of War.

Top administration officials also have preparing a new national defense strategy that is expected to make homeland defense the nation’s top concern, after several years of China being identified as the top national security risk to the United States. Some officials familiar with the order to travel said they thought that may come up.

Hegseth’s directive in May to slash about 100 generals and admirals also has generated concern among top military leaders. He called then for a “minimum” 20 percent cut to the number of four-star officers — the military’s top rank — on active duty and a corresponding number of generals in the National Guard. There also will be another 10 percent reduction, at least, to the total number of generals and admirals across the force.

Last month Hegseth fired Lt. Gen. Jeffrey Kruse, director of the Defense Intelligence Agency; Vice Adm. Nancy Lacore, the chief of the Navy Reserve; and Rear Adm. Milton Sands, a Navy SEAL officer who oversaw Naval Special Warfare Command. No specific reason was given in either case.

The firings were the latest in a wider purge of national security agencies’ top ranks. Since entering office, the Trump administration also has fired the chairman of the Joint Chiefs of Staff, Gen. Charles Q. Brown Jr.; the chief of naval operations, Adm. Lisa Franchetti; the commandant of the Coast Guard, Adm. Linda Fagan; and the Air Force vice chief of staff, Gen. James Slife among others. The list includes a disproportionate number of women.

Gen. David Allvin, the chief of staff of the Air Force, announced last month he will step down in November, after he was asked to retire.