Is it easier to keep secrets when you have fewer of them? Senator Daniel Patrick Moynihan seemed to think so. Twenty years ago, he was chairman of the Commission on Protecting and Reducing Government Secrecy, insisting that the ‘‘protecting’’ and the ‘‘reducing’’ parts went hand in hand — that in order to safeguard the secrets that really mattered, those secrets would have to be few and far between. The commission combed through a long history of protected information, concerning everything from bomb tests to Communist infiltration, before calling for a vast reduction in the amount of federal information deemed ‘‘classified.’’ Moynihan hoped that the end of the Cold War had made Washington’s pernicious ‘‘culture of secrecy’’ obsolete. But history did not go his way. Congress continues to hold hearings on the same stubborn problem, and every year, the state continues to generate tens of millions of new classified documents.

During the campaign, Donald Trump repeatedly accused Hillary Clinton of endangering national security by keeping classified email on a private server. Already, though, his administration has helped show how confusing and how politicized classification can be. As president, he seems to have only the foggiest idea of how to handle such information himself: He reportedly divulged ‘‘highly classified’’ material from an undercover ISIS operative to the Russian foreign minister right in the Oval Office. And in August, he retweeted a Fox News report featuring leaked intelligence about North Korea — even as Nikki Haley, his own United Nations Ambassador, refused to discuss it, explaining that she ‘‘can’t talk about anything that’s classified.’’

Trump has been merciless toward anyone else in government who reveals his administration’s secrets, tweeting that ‘‘the real story that Congress, the F.B.I. and all others should be looking into is the leaking of Classified information.’’ This summer, after the former F.B.I. director James Comey produced what he said were unclassified personal notes on their meetings, Trump complained that ‘‘Comey leaked CLASSIFIED INFORMATION to the media. That is so illegal!’’

This marks a shift from the Obama years, when the debate over classified information focused on military and intelligence revelations, from the likes of Chelsea Manning and Edward Snowden. Under Trump, things are more personal. ‘‘What’s new,’’ says the Columbia University historian Matthew Connelly, author of a forthcoming history of government classification, ‘‘is the volume and sensitivity of what’s being leaked and the fact that at least some of these leaks seem intended to show Trump is unfit to be president.’’ ‘‘Classified’’ still conjures images of top-secret government plots, but in Trump’s Washington, it’s more often used to describe information that the president would prefer to keep quiet, from allegations of collusion to reports of White House infighting. What started out as a way to safeguard national security has also become a means of protecting — or destroying — the president himself.