The White House denied that President Trump was briefed on the classified assessment, even though his staff has been discussing the matter since March.

Trump had been briefed on the months-old classified intelligence assessment about Russia’s activities.

The officials briefed on the matter said the intelligence assessment was based at least in part on interrogations of captured Afghan militants and criminals.

The officials said the assessment had been treated as a closely held secret but that the administration expanded briefings about it over the past week — including sharing information about it with the British government, whose forces are among those said to have been targeted.

director, national security adviser and the chief of staff can all confirm that neither the president nor the vice president were briefed on the alleged Russian bounty intelligence,” the White House press secretary, Kayleigh McEnany, said in a statement Saturday afternoon, about 25 hours after the article was posted on The Times’s website.

But one American official had told The Times that the intelligence finding that the Russians had offered and paid bounties to Afghan militants and criminals had been briefed at the highest levels of the White House.

McEnany notably did not question the substance of the intelligence assessment, saying only that her statement “did not speak to the merit of the alleged intelligence.” She also did not challenge the Times’s reporting that the National Security Council had convened an interagency meeting about what to do about the report in late March.

American officials reached on Saturday said it strained credulity to think that White House national-security officials would be discussing such an important matter for months and even brief British officials about it and never provide the information to Mr.

McEnany also said in her statement that “the United States receives thousands of intelligence reports a day and they are subject to strict scrutiny.” It was not clear why she portrayed the report as if it were a tip merely received by the government from an outside source, when it was instead an intelligence assessment developed by the American government itself, based on analyzing intelligence.

Trump is particularly difficult to brief on critical national security matters, according to a recent examination by The Times that drew on interviews with 10 current and former intelligence officials familiar with his intelligence briefings.

Trump is said to have chosen to sit for intelligence briefings two or three times a week, rather than every day.

Trump but sometimes tries to push him to more hawkish positions — such as opposing his plan to pull out of Syria — said on Twitter that he wanted the administration to take the intelligence assessment seriously and brief Congress on the matter.

In response to the intelligence assessment, senior administration aides developed an array of potential options — starting with making a diplomatic complaint to Moscow and a demand that it stop, along with an escalating series of sanctions and other more aggressive possible responses, according to officials familiar with internal deliberations.

But the White House has yet to decide on taking any step, the officials said in recent days.

The officials familiar with the intelligence did not explain the White House’s delay in deciding how to respond to the intelligence about Russia.