A supporter of President-elect Donald Trump takes a photo of him on her smartphone at a rally in Baton Rouge, La., on Friday. (Don Emmert/Agence France-Presse via Getty Images)

THE STRONGEST indication that the Obama administration has not adequately disclosed or responded to Russian interference in the presidential election may be that President-elect Donald Trump still denies that it happened. “I don’t believe they interfered,” Mr. Trump told Time magazine last week, adding that computer hacking of state election authorities and the theft and release of emails from the Democratic National Committee “could be some guy in his home in New Jersey.”

Mr. Trump has surely been briefed by U.S. intelligence agencies on the evidence that caused them to publicly accuse Russia of interference, and that prompted President Obama to use the nuclear hotline to warn the regime of Vladi­mir Putin against further “malicious cyberactivity.” But Mr. Trump probably calculates he can get away with flouting the facts — and continue his bromance with Mr. Putin — because the White House has neither made public what it knows about the Russian hacking nor adopted any punitive measures.

That must change before Mr. Obama leaves office. On Friday, under pressure from both Democratic and Republican members of Congress, the president’s homeland security adviser disclosed that a “full review” of Russian actions during the election campaign had been ordered. White House aide Lisa Monaco said the interference “may have crossed into a new threshold, and it is incumbent upon us to take stock of that . . . to understand what has happened and to impart some lessons learned.”

A full review is appropriate. The intelligence agencies and those they have briefed in Congress appear to have a high degree of confidence about Russia’s responsibility. As Ms. Monaco indicated, what occurred was not merely espionage, which the United States as well as Russia routinely engage in, but a deliberate attempt to sabotage the U.S. election: The Post reported the CIA had concluded that Moscow’s aim was to help Mr. Trump defeat Hillary Clinton. Moreover, the operation was part of a broader Russian assault on Western democracies: Moscow’s hackers went on to target Italy’s government in a constitutional referendum, and, according to the German intelligence service, are already seeking to disrupt Germany’s incipient election campaign.

Consequently, it is crucial that the “lessons learned” in the administration’s review be imparted not just in classified briefings but also to the world — and that the Kremlin suffer some consequences for its actions. Those in Russia who conducted the election hacks should be named, banned from travel and targeted for asset freezes. If possible, they should be prosecuted. A public disclosure of U.S. intelligence about Mr. Putin’s regime — evidence of corruption, for example — would be appropriate.

It’s encouraging that congressional leaders from both parties are seeking to hold Russia accountable. Seven Democratic senators on the intelligence committee sent Mr. Obama a letter last month calling for the declassification and release of “additional information concerning the Russian Government and the U.S. election” and noting that a more detailed request had been conveyed through classified channels. Republican Sens. Lindsay O. Graham (S.C.), Bob Corker (Tenn.) and John McCain (Ariz.) say they are planning hearings on various aspects of Russian cyber-activity, including attempted incursions into U.S. weapons systems.

It is Mr. Obama, however, who has the means and the obligation to act before he leaves office. If Mr. Trump is inaugurated without disclosure of the role Moscow played in his election, the meddling is likely to remain undisclosed and unpunished. Mr. Obama should ensure that it is, at least, undeniable.