On Monday, Ambassador Tina Kaidanow, who was a longstanding employee of the State Department before transitioning into her new role as senior adviser for international cooperation with the Defense Department, announced her resignation. Michael Vaccaro, the Pentagon’s Director for International Armaments Cooperation, will step in and fill the role until a replacement can be identified. Kaidanow’s departure alone may not have been enough to garner much attention from the press, but her’s is only the latest in what some are calling an “exodus” of Pentagon officials — as five have now announced their intent to leave in just the past week.

“The department remains committed to the development and implementation of international cooperative programs and defense exportability efforts to foster cooperation with U.S. allies on research, development, production and support of weapons systems and related equipment,” Lt. Col. Michael Andrews said in a statement. “The department will not provide anything further on this personnel matter.”

Prior to Kaidanow’s announcement, four other officials notified the Defense Department of their intent to leave their positions this week. Those departures include Randal Schriver, the Pentagon’s senior Asia policy official; Jimmy Stewart, who has been serving as the acting Undersecretary of Defense for Personnel and Readiness since October 2018; Steven Walker, the head of the Pentagon’s secretive Defense Advanced Research Projects Agency (DARPA); and Kari Bingen, principal Deputy Undersecretary of Defense for Intelligence.

These departures highlight an ongoing issue within the Pentagon, as departures are often filled with “acting” replacements, leading to concerns about the stability of leadership within the upper echelons of America’s defense infrastructure. Even Defense Secretary Mark Esper, who stepped in after Patrick Shanahan filled the role in an “acting” capacity for nearly a year and a half, acknowledged the lacking stability among the military’s civilian leadership in August. He expects billets that have been standing vacant for some time to soon be filled.

Those vacant billets, which Esper spoke of at the time, obviously don’t include this week’s departures. Instead, he was likely referencing a number of other positions that were unfilled at the time and remain unfilled today — including six of the 21 deputy assistant secretary of defense for policy positions.

This lack of stable leadership can have far reaching ramifications on defense policy and its enactment. As Senator Jack Reed (D-RI), a ranking member of the Senate Armed Services Committee, warned in referencing these gaps, “you’re not anticipating problems and you’re not as well-prepared to respond to problems. So this is a very difficult problem.”

The Defense Department isn’t the only military-related agency that’s suffered from a lack of consistent leadership in recent years. The Department of Veterans Affairs has also seen a number of departures and empty positions, most notably at the secretary level. Since January of 2017, the VA has seen its top position change hands five different times, with three changes in 2018 alone. The VA has even cited these frequent leadership changes as among their reasons for failing to follow through on suicide prevention outreach initiatives that were funded and never executed.