Three years ago tonight, I took one last look back at the White House, lit brilliantly against the night sky, as I walked out the front gates onto Pennsylvania Avenue. It’s the same look back I’d given the building each night for over two years as I left after a long day of work at the National Security Council. But this time was different: this time, I didn’t know when I might be back, whether as a government official or as a private citizen.

After six weeks of a normal transition with my terrific Trump administration successor (in contrast to an overall wildly abnormal transition throughout the federal government), I knew firsthand that things were changing—a lot. President Donald Trump had issued his first attempt at a travel ban and been rejected by multiple federal courts; fired his first Acting Attorney General, Sally Yates, when she declined to defend the ban in court; and forced out his first National Security Advisor, Michael Flynn, for—in essence—creating national insecurity when Flynn lied to the Vice President about conversations with the Russian ambassador during the transition. I was a civil servant who’d never been political, formally or informally; but already, as I looked back at that brightly lit White House, I yearned to see things go back to something more normal: more lawful, more sensible, more responsible.

I’ve held that image in my head for three years now—that look back to the fast-fading remnants of a normal White House, a normal government, a normal time. Just as the memory gets a little fuzzier in my mind’s eye with every passing day, the American people’s sense of what’s normal erodes a bit with every latest Trump outrage. As the months go by, a core challenge for all of us who know what normal looks like is figuring out how to help the country refuse to let the abnormal become the norm—at least this form of abnormal, Trump’s brand of abnormal.

Under any new president, change is normal. We should expect changes in policies, even changes in legal positions. But Trump’s changes are not normal. And they can’t be explained as the actions of a principled norm disruptor who needs to shake up settled institutions in order to deliver for the American people. No, the changes of the past three years represent the deliberate demolition of the very institutions that any president actually relies on to carry out his or her changes in policies and legal positions.

Take the National Security Council itself. Trump’s last two National Security Advisors, John Bolton and Robert O’Brien, have intentionally destroyed that institution.

Bolton did it as a power play. He calculated that he could exert more influence on Trump (and thus on American foreign policy) if he shriveled an apparatus designed to bring to the president the views of officials from across the government. Instead, Bolton just spent as much time around Trump as possible, whispering in his ear. It’s a terrible legacy for the country, though it’s hard to say that Bolton sized up Trump incorrectly.

Then O’Brien did it to appease Trump. O’Brien indulged Trump’s wrath that National Security Council officials had testified during impeachment proceedings by purporting to “rightsize” the NSC by eliminating dozens of NSC officials—including having security escort out one who testified (and, even more preposterously, his brother).

But it’s not just the National Security Council or the broader White House. It’s the federal government as a whole that’s changed in decidedly abnormal, harmful ways. A staggering number of talented intelligence officers, diplomats, lawyers, investigators, policy officials, and even members of the armed forces have left the government. What’s more, the corruption introduced by cabinet members who’ve abused public office for private gain can’t be instantly reversed. Indeed, the experience of foreign countries shows that a culture of corruption, once it takes root, is difficult to eradicate.

And our government has been—again, deliberately—broken in ways that can’t quickly be repaired. Lawyers’ advice has gone unheeded. Intelligence officials’ analysis has been suppressed. Scientists have been silenced. Sure, some civil servants leave the government during any administration, and some processes change. But the exodus and the suppression under Trump aren’t normal—and they’re the very kinds of abnormality that make us weaker, more vulnerable as a nation.

This profound sense of Trump’s abnormality has fueled the past few years’ steady stream of letters signed by hundreds, even thousands, of “formers.” Former national security officials; former Justice Department lawyers; former members of the armed forces: The letters just keep on coming. And the reason is that those who know what normal is (and value it) want—desperately—to make the broader public understand what’s not normal and dangerous about the Trump presidency. That’s, ultimately, what these letters signify—a large group of people who’ve served under presidents of both parties saying that what’s happening right now is decidedly alarming. Normal is lawful. Normal is fact-driven, intelligence-driven, science-driven. Normal is methodical and coordinated, not impulsive and erratic. Normal is driven by the best interests of the nation collectively, not the best interests of the president personally. Normal can be trusted. Normal is respectful, even in disagreement. Trump is none of this, as the letters keep reminding us. To be a norm disruptor is one thing, and even beneficial at times. But to break these particular norms is beyond reason and principle.

That said, it’s not easy to keep this up. Just look at the past four weeks since Trump was acquitted in his Senate impeachment trial. It’s wildly abnormal to retaliate against NSC officials, an EU Ambassador, a Treasury Undersecretary nominee, a Defense Department comptroller nominee, and more because they did their jobs. It’s wildly abnormal for the Justice Department abruptly to reverse itself—twice, in Flynn’s case and then Stone’s—and suggest lower sentences for close associates of the President than the Department’s career prosecutors had just recommended to federal courts. It’s wildly abnormal to punish the Acting Director of National Intelligence because a top official working for him had briefed Congress on the intelligence community’s assessment of 2020 election interference, let alone to replace him unexpectedly with an ambassador best known for his pugnacious tweets.

So here’s a central challenge as the Trump presidency gruelingly lumbers on: making sure that Trump’s relentless abnormality doesn’t become the new normal. After each of these abnormal incidents I’ve just described, those who know what normal is have more or less gone ballistic, denouncing what Trump has done in op-eds, on television, on radio, and—of course—in letters garnering scores of signatures from former officials. To many Americans, this can seem like overkill. One hears them asking, How can it always be so bad? Alas, the answer with Trump is that it is—it’s bad and getting acutely worse. The challenge, three years in, is never to lose sight of that White House shining brightly under the darkened sky some three years ago; to never lose sight of what normal—lawful, sensible, responsible—really is and why it matters.