RUSSIAN PRESIDENT Vladimir Putin and his administration in Moscow tried to influence the 2020 presidential election. We already knew this, but that doesn’t make the conclusions in a declassified U.S. intelligence report issued Tuesday any less alarming.

The Office of the Director of National Intelligence, in the government’s first released review of foreign meddling after the election, said that Russia undercut President Biden’s candidacy; Iran carried out a covert campaign to damage then-President Donald Trump’s; and China considered interfering but decided against it. Yet even Russia’s salvo, it appears, paled in comparison to its 2016 assault on the integrity of our democracy — and no foreign actor attempted to tamper with the votes or results themselves. Expert warnings that domestic disruptions were the deeper threat proved prophetic. Indeed, even this report on adversaries abroad reveals a homegrown problem: We are our often own worst enemy.

The Kremlin’s strategy this cycle relied less on its army of trolls marching across social media sites, and more on infiltrating this country’s own ranks: spreading narratives indirectly through proxies rather than directly in the manner platforms have learned to detect. The report focuses most closely on the failed attempts by a network of Ukraine-linked individuals, such as legislator Andriy Derkach and Konstantin Kilimnik, to persuade prominent people and media outlets to launder their false narratives about Mr. Biden. The two were found out — but they managed to secure repeated meetings with Rudolph W. Giuliani and persuade the television network One America News to air a propagandistic documentary.

This bears repeating: The onetime personal lawyer of a president who displayed an unexplained affinity for Mr. Putin was either duped into participating in an interference operation personally authorized by the dictator, or he participated willingly. The president himself happily spread the same conspiracy theories that the Kremlin sought to seed. Mr. Trump and his allies also created another story of a rigged election that Russian trolls promoted in turn. Indeed, Russia may not have tried as hard as it did last time around to sow discord and doubt in the legitimacy of the vote. But that’s in part because it didn’t have to. The United States’ citizens and leaders were sowing discord and doubt enough on their own.

The new administration is likely to do more than its predecessor to discourage Mr. Putin, whom Mr. Biden on Wednesday said would “pay a price.” But this week’s report doesn’t anticipate that Russia will stop meddling anytime soon. The White House, the rest of the government and the rest of the nation can also protect themselves from whatever attacks do come by building trust, keeping on guard and refusing to play along.

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