On Wednesday, Lt. Col. Alexander Vindman announced he would be retiring from the U.S. Army as a result of retaliation from the White House and senior officials in the Department of Defense.

Last fall, Vindman testified under subpoena during the House’s impeachment hearings about his concerns regarding President Trump’s phone call to Ukrainian President Volodymyr Zelensky. His testimony set up a civil-military conflict that pitted the president against a mid-level officer and Congress.

While defense officials had promised there would be no retaliation, Vindman was told by senior Army officials that there were “forces working against his advancement within the military” as a result of his testimony.

The Vindman endgame is part of a larger pattern of civil-military conflict in the Trump administration. Trump himself has signed campaign paraphernalia on military bases, excoriated his political opponents in speeches to the troops, referred to senior military officers as “my generals,” intervened in matters of military justice, and advocated for using the military against protesters — to name just a few.

Each incident might appear hardly noteworthy for civil-military relations, as I have argued here at TMC before. But taken together, the regular politicization of military affairs by a sitting president can have important and negative consequences on civil-military relations and the ability of the armed forces to recruit, retain and fight effectively in the future. Here’s how.

Politicization inhibits the military’s ability to promote top talent

In 2018 Vindman joined the National Security Council, an assignment reserved for the Army’s top-performing and most promising officers. His scheduled follow-on assignment to attend the National War College suggests the Army once expected him to go on to senior leadership positions.

But his testimony last fall angered many Republicans and appears to have effectively ended a once-promising career — much to the dismay of prominent voices in civil-military relations.

Of course, many appointments to top military posts are political — subject to presidential and congressional preferences, among other factors — as Jim Golby wrote here at TMC when Gen. Mark Milley was appointed chairman of the Joint Chiefs of Staff in 2019. But the interference in Vindman’s career advancement is unusual precisely because he is a mid-level officer in the midst of an expected promotion, and may undermine the pipeline of military talent flowing to the top.

Politicization degrades command structures

Politicization of the military by civilians can also negatively affect how military officers interact with one another and create a gap between senior and mid-level officers. This gap can then contribute to a pervasive attitude that mid-level officers cannot give bad or unflattering news to their commanders. Indeed, retired Adm. Mike Mullen’s biggest concern this spring — when the administration was accused of silencing Navy Capt.. Brett Crozier’s concerns about the coronavirus — that it “significantly negatively impacts the willingness of commanders to speak truth to power.”

While Secretary of Defense Mark T. Esper had publicly said Vindman would not be punished, it appears senior Army officers felt differently, suggesting he needed a “rehabilitative assignment” after his year at the National War College.

What’s more, since the Fat Leonard scandal, collision of two Navy ships and the Crozier affair, the military has been consumed by accusations that it suffers from a crisis in trust and confidence. Political retaliation against low-ranking officers has, according to some reports, become expected, and sends a strong signal to emerging senior leaders about what kind of behavior is rewarded.

The response to overt politicization among subordinates is also predictable: Morale declines as troops feel abandoned by their senior leadership. We saw this in March after the relief of Brett Crozier — morale among sailors on the Roosevelt was reported to be “in the toilet” after the dismissal of a beloved skipper for apparently political reasons.

All of this is problematic because research shows one of the biggest advantages that democracies have during war is the initiative and leadership of its officers. Politicization robs democracies of some of their warfighting advantage.

Politicization compromises the military’s relationship with society

When the military appears to serve the political preferences of a single party, they lose recruits, legitimacy and the popular support necessary to maintain a large force that projects power around the world.

When civilian leaders inject partisan politics into military affairs, it undermines the military’s ability to recruit and retain from all cross-sections of society. Military volunteers already come disproportionately from the South and legacy military families, and surveys also show military members more openly identify as (Republican) partisans than they did previously.

Such concerns explain the military’s fierce reaction in June when Trump used National Guard forces to dispel peaceful protesters near the White House for a presidential photo op in front of St. John’s Church. Over a dozen retired general officers decried the politicization of the military — including former secretary of defense Jim Mattis. Gen. Milley later apologized for joining the photo op, citing concern about “the role of the military in civil society.”

Politicization undermines civilian control and military effectiveness

When civilian leaders inject partisan politics into military affairs, civil-military conflict becomes much more likely. Military leaders feel forced to push back against civilian leaders, and can become resentful and distrustful of the president’s orders and intentions. This undermines civilian control and jeopardizes the ability of the president to wage war on behalf of the nation.

Even when civilians don’t directly order an action, military leaders make decisions anticipating political needs, a phenomenon that I call “indirect politicization.” This form of politicization is particularly damaging because it compromises the recommendations civilians receive from their military advisers. This significantly reduces civilian leaders’ options as well as military effectiveness, since officers may adjust operations and tactics to conform to domestic politics rather than the rhythm of war.

Vindman’s early retirement is yet another signal that civil-military relations in the U.S. are becoming increasingly politicized. While Vindman is only one officer, his departure reflects trends that will have an impact on military recruitment, retention and effectiveness.

Carrie A. Lee is an assistant professor at the U.S. Air War College. You can follow her on Twitter at @CarrieALee1. Opinions and conclusions expressed in this piece are the author’s own and not the official position or opinion of the U.S. government, U.S. Air Force, or Air War College.