Leaders must be held accountable for their actions if the rule of law is to prevail. For the military, accountability derives from civilian control over our armed forces. This is the governing principle of civil-military relations; it is central to our democracy and peaceful society.

General Mark Milley subverted that principle.

Milley, the chairman of the Joint Chiefs of Staff, had justifiably deep concerns on multiple occasions regarding an unhinged and increasingly erratic President Donald Trump, according to new reporting by Bob Woodward and Robert Costa of The Washington Post in their book, Peril; the Post’s Carol Leonnig and Phil Rucker in their book, I Alone Can Fix It; and Susan Glasser, of The New Yorker. In those moments, Milley attempted to engage with White House and National Security Council staff to counsel the President to reverse course. This was appropriate action; it was similar to the way I reported the abuse of power that resulted in Trump’s first impeachment. Ultimately, when duty demanded, I went further — I publicly testified before Congress about a phone call between Trump and Ukrainian president Volodymyr Zelensky, in which Trump encouraged Zelensky to investigate Joe Biden, his political rival.

But now these reports, months after the danger has passed, show that when Milley failed to achieve results using normal channels, his next steps were far more controversial. Milley, fearing that the post-election crisis was Trump’s “Reichstag moment”, whereby the President would either use the military to prevent the peaceful transfer of power or push the United States into a war, expressed concerns to his military subordinates that Trump was dangerous. He made clear that any orders from Trump to employ nuclear forces must be routed through him. If Milley confirms this reporting in his testimony before Congress on September 28, only two actions can restore the crucial balance of civil-military relations: Either Milley resigns or President Joe Biden relieves him of his duties as chairman of the Joint Chiefs.

What were Milley’s options in the untenable situation he faced in the hours and days after Trump’s efforts to steal the election and instigate an insurrection to overturn Biden’s legitimate victory? There happens to be a recent and excellent precedent. In early 2019, retired general Jim Mattis resigned as secretary of defence in protest over Trump’s ill-considered decision to hastily and dangerously withdraw all forces from Syria and abandon our Kurdish allies. Mattis’s resignation resulted in an enormous backlash, compelling Trump to reverse his decision. Mattis put his convictions and US national security interests ahead of his position.

Imagine Milley doing the same on January 7, the day after Trump supporters stormed the Capitol. How might that have restrained the President and affected the second impeachment trial that followed the insurrection? A resignation accompanied by a letter similar to Mattis’s would have shed light on the seriousness of the situation inside the White House. In addition, Milley could have publicly expressed his concerns and joined other senior leaders, including Cabinet officials, who stepped down after January 6, which would have been a proactive move against further abuse of power.

Instead, the reporting suggests, Milley blustered to subordinates, raised grave concerns with House Speaker Nancy Pelosi and, sometime in the same period, sought to circumvent or subvert the chain of command.

The Joint Chiefs of Staff consist of more than a half-dozen four-star military officers, each with several decades of honourable service and dedication to defending the US Constitution against all enemies foreign and domestic. I am befuddled by the notion that only Milley was standing between a madman and Armageddon. That is the plot of a Hollywood blockbuster. That is not the way the US military operates. Any one of the other chiefs of staff or the vice-chairman would have stepped up and continued to serve as a guardrail. Milley’s resignation would have put people on alert and made it nearly impossible for Trump to use the military to extend his presidency. The vice-chairman automatically would have served as the new chairman until the Senate was able to confirm a replacement.

Milley did not resign in protest over the events that unfolded in the closing days of the Trump Administration, the moment when such action would have been most meaningful to illuminate his concerns and when other generals were available to provide the necessary checks. Instead, the public learnt of his fears only months later. The chairman of the Joint Chiefs of Staff did not act when it would have made a difference; that is consequential.

Public servants have long protected citizens against abuses by self-serving political actors. They were the check on the Trump Administration and testified to the President's corruption. While institutional norms were harmed and good order eroded, the institutions themselves held. What Trump could not do in four years to subvert the proper functioning of our government, he could not easily have done in the waning days of his administration. The failure of the insurrection and the failure to overturn the election are testament to that. It is very dangerous to believe that any one individual in a system is indispensable. Too many of our leaders believe that about themselves.

Milley has been at the centre of a firestorm on multiple occasions during his tenure; he may be the most controversial active-duty general since Douglas MacArthur, who was relieved of his duties after he subverted the chain of command and publicly clashed with President Harry Truman over US foreign policy in Korea. Trump paraded Milley through Lafayette Square in front of the White House after the violent suppression of a peaceful protest over the murder of George Floyd; Milley later apologised for his poor judgment in participating as a prop for the President.

The Left has accused him of a slow response to the insurrection on January 6, and the Right has charged him with being insubordinate and leading a “woke” military. Both sides have accused him of undermining civilian control of the military. Supporters and detractors alike have come to see him as a political actor. Such a reputation harms an honourable institution that espouses apolitical values. Furthermore, it undermines the military’s credibility at a moment of real national security threats.

In recent years, too many leaders have succumbed to situational ethics, and the public have looked the other way when people considered those leaders part of their faction. Doing the wrong thing, even for the right reasons, must have consequences. Many people in the Trump Administration — including me — resigned or were fired exactly because they did the right things in the right way. Milley may have done the wrong thing for the right reasons. But the chairman of the Joint Chiefs of Staff does not deserve greater consideration for doing the wrong thing — he deserves greater scrutiny.

As my friend and former Pentagon official John Gans tweeted: “You can break norms for a greater good, but that often comes with a price. Paying it is the only way to ensure the norms survive for the next time.”

If we want our institutions to be our guardrails rather than relying on a constant supply of individual saviours, we should hold our leaders accountable. Truman wrote in his 1956 memoir: “If there is one basic element in our Constitution, it is civilian control of the military. Policies are to be made by the elected political officials, not by generals or admirals.”

That is why he relieved MacArthur of his duties. So far Biden has expressed his confidence in Milley, but the precedent here is important. Right matters only when everyone’s actions have consequences.

• Alexander S. Vindman, a retired US Army lieutenant-colonel, is a doctoral student and fellow of the Foreign Policy Institute at the Johns Hopkins School of Advanced International Studies, a Pritzker military fellow at the Lawfare Institute and the author of the memoir Here, Right Matters. He previously served as the director for European affairs on the National Security Council, as the political-military affairs officer for Russia for the chairman of the Joint Chiefs of Staff and as an attaché at the US Embassy in Moscow