U.S. thinks The Kremlin is behind hacking of Democratic emails.

WASHINGTON — U.S. intelligence agencies have told the White House they now have “high confidence” that the Russian government was behind the theft of emails and documents from the Democratic National Committee, according to federal officials who have been briefed on the evidence.

But intelligence agencies have cautioned that they are uncertain whether the electronic break-in at the committee’s computer systems was intended as fairly routine cyberespionage — of the kind the United States also conducts around the world — or as part of an effort to manipulate the 2016 presidential election.

The emails were released by WikiLeaks, whose founder, Julian Assange has made it clear that he hoped to harm Hillary Clinton’s chances of winning the presidency.

The assessment by the intelligence community of Russian involvement in the DNC hack, which largely echoes the findings of private cybersecurity firms that have examined the electronic fingerprints left by the intruders, leaves President Barack Obama and his national security aides with a difficult diplomatic and political decision: Whether to publicly accuse the government of President Vladimir Putin with engineering the hack.

Such a public accusation could result in a further deterioration of the already icy relationship between Washington and Moscow, at a moment when the administration is trying to reach an accord with Mr. Putin on a cease-fire in Syria and on other issues.

Asked on Tuesday whether Moscow was trying to influence the presidential election, Mr. Obama said, “Anything’s possible.”

He added that the hack of party records was characteristic of Russian government behavior and suggesting a potential motive for that country to meddle in the U.S. presidential election.

“What we do know is that the Russians hack our systems, not just government systems but private systems,” Mr. Obama told NBC. “What the motives were in terms of the leaks, all that — I can’t say directly. What I do know is that Donald Trump has repeatedly expressed admiration for Vladimir Putin.”

Stealing information about another country’s political infighting is hardly new, and the U.S. has conducted covert collection from allies like Germany and adversaries like Russia for decades. Publishing the documents — what some have called “weaponizing” them — is a different issue. Ms. Clinton’s campaign has suggested that Mr. Putin was trying to even the score after the former secretary of state denounced a 2011 Russian election as filled with fraud.

Campaign officials have also suggested that Mr. Putin could be trying to tilt the election to Mr. Trump. But they acknowledge that they have no evidence.

And experts who’ve followed the leak said Tuesday that they believe the party’s claim that Moscow had a hand in the hack, lending weight to the extraordinary allegation that the Kremlin is trying to tamper with the U.S. presidential contest.

Secretary of State John Kerry raised the attack on the DNC with his Russian counterpart, Sergey Lavrov, on Tuesday at a meeting of foreign ministers in Vientiane, Laos. Mr. Lavrov dismissed the idea that Russia was involved, telling reporters who asked about the charges: “I don’t want to use four-letter words.” The Washington Post and Associated Press contributed.