Andrew Harnik / AP

WASHINGTON — As a political underdog and now as president-elect, Donald Trump has employed the same brutal but effective go-to move when he’s tweeted or talked himself into an impasse:

Attack the attacker.

That aggressiveness served him well in the presidential campaign, and allowed him to muscle through scandals and self-inflicted management mistakes that would have scuttled a lesser politician. But Trump’s postelection effort to minimize intelligence assessments about Russia’s actions came to an abrupt end Friday after a detailed classified briefing from the nation’s top intelligence officials at Trump Tower and the release of an unclassified report concluding that the Russian president, Vladimir Putin, had a “clear preference” for Trump.

By the end of the day, it was clear that the strategy of intimidation and bluster that served Trump so well in the presidential campaign would not prove nearly as effective in Washington.Here was a reminder, should Trump heed it, that a president’s critics, especially the lords of Washington’s national security establishment, can’t always be cowed by a flash-grenade tweet or a withering quip about the possibility that a “400-lb. hacker” might have breached Democratic servers.

“I don’t think what worked in a campaign against Jeb Bush is really going to work when you are dealing, you know, with the combined power of the CIA, NSA and the FBI,” said John Weaver, a frequent critic of Trump who worked on Ohio Gov. John Kasich’s unsuccessful primary campaign against him.

Sen. Chuck Schumer, D-N.Y., who has a good working relationship with Trump, warned him recently that it was “really dumb” to take on the intelligence services. He followed up with a warning Wednesday that the president-elect needed “to calm down” his Twitter use.

He’s not alone. In recent days, Trump’s aides have gently prodded him to drop the attacks on the intelligence community and mollify nervous Republicans by showing that he was moving ahead with forward-looking reforms of the sprawling intelligence-gathering bureaucracy, according to two people close to the discussions. “He can’t afford this fight,” one longtime adviser to Trump said. “He’s said it’s time to move on — well, move on.”

The decision to choose Dan Coats, a popular former senator from Indiana, as director of national intelligence had been in the works for some time, the officials said, but Trump’s advisers decided to announce the choice to ease concerns of a rift between the future Trump White House and the clandestine services.

It is less clear if Trump’s admission reflects a long-term shift in strategy to appease his advisers or a momentary decision to escape a negative news cycle.

In the weeks leading up to the release of the report, the president-elect repeatedly cast doubt on an emerging consensus among intelligence officials, outside analysts and legislators from both parties that Putin had attempted to interfere with the election. As recently as Tuesday, Trump mused on Twitter that his classified briefing may have been postponed to cook the results. “The ‘Intelligence’ briefing on so-called ‘Russian hacking’ was delayed until Friday, perhaps more time needed to build a case. Very strange!”

Officials denied that charge, and James R. Clapper Jr., director of national intelligence, told the Senate Armed Services Committee on Thursday that he was concerned about “disparagement of the U.S. intelligence community.”

By Friday morning, he was still defiant, but there was a substantial, if subtle, shift in tone, reflecting Trump’s penchant for masking a change in tune by keeping the volume at full blast. He began pushing blame from the national security establishment to a pair of his favorite political chew toys — Democrats and the news media.

Early in the day, a fired-up Trump said in an interview that he was the victim of a “political witch hunt” aimed at discrediting his presidency before it began. He suggested that the culprits were supporters of Hillary Clinton who were “very embarrassed” by her loss.

A short time later, before he was due to receive the classified briefing, he tweeted out a rebuke of NBC for broadcasting a Thursday night report on the intelligence agencies’ findings.

“I am asking the chairs of the House and Senate committees to investigate top secret intelligence shared with NBC prior to me seeing it,” Trump wrote.

And finally, after the meeting, he released a grudging statement: “Whether it is our government, organizations, associations or businesses we need to aggressively combat and stop cyberattacks.”

Members of Trump’s party seemed unwilling to give him any leeway on the hacking issue, prodding him toward a more aggressive stance in confronting Russia.

“The men and women of our intelligence community are unparalleled,” said Sen. Ben Sasse, R-Neb., a frequent critic of Trump. “Where is the urgency to make it clear to our adversaries that these attacks aren’t cost-free?”

And as Thursday’s Armed Services Committee hearing showed, Senate Republicans, led by John McCain of Arizona, chairman of the committee, are intent on shielding the intelligence agencies from any attack, even one waged by their own president.

“McCain just got elected to a new six-year-term,” said Weaver, a longtime adviser of McCain. “He’s not going to let anyone attack people who protect the country’s interests, and he’s got nothing to lose.”