Candidate Donald Trump often said he knew more when it came to the country’s foes than America’s top military leaders. But by siding with retired and current four-star generals on Afghanistan, Trump placed a big bet on a group he once believed had been “reduced to rubble.”

Trump announced Monday night at Joint Base Fort Myer Hamilton Hall in Arlington, Va., he will keep thousands of U.S. troops in Afghanistan despite his long-held disdain for the operation there. The president’s decision came after a months-long review by his national security team, and reports indicate he will raise the American military presence there to around 12,000.

He also announced a revised strategy that features a larger focus on counterterrorism operations and putting more pressure on Pakistan, where U.S. foes often flee for safe haven.

“In the end, we will win,” Trump said.

The commander in chief candidly admitted his instincts told him to “pull out” all American forces. Even before he entered the 2016 presidential race, the then-reality television star and real estate mogul made clear his feelings about the Afghanistan operation, in 2012 calling it a “complete waste.”

Comments like that show how deciding to keep American troops there amounts to a major policy flip-flop for Trump — and just how much trust he has placed in a group he often refers to as “my generals.” In fact, Trump made clear he decided to remove the shackles many military commanders and frontline troops felt former President Barack Obama placed on their ability to carry out the operation.

[Beefing Up Afghan Troop Level Would Be Major Shift for Trump]

“We are not nation-building again,” Trump said of his Afghanistan strategy. “We are killing terrorists.”

Trump’s decision to follow his generals was well received by Republicans on Capitol Hill who felt the Obama administration too often overruled commanders in theater. Lawmakers undoubtedly will debate the new strategy when they return next month. It could become part of a debate about whether to update the post-9/11 measure passed to authorize the Afghanistan conflict, a nearly 16-year-old authorization that some lawmakers say needs to be modernized.

The collective fingerprints of the current and former generals involved in the Afghanistan review were visible throughout Trump’s speech, which he read in a slow and careful cadence in front of an audience of military personnel and senior aides.

That was true of one portion in particular, in which the president revealed he has “already lifted restrictions the previous administration placed on our warfighters that prevented the secretary of Defense and our commanders in the field from fully and swiftly waging battle against the enemy.”

“Micromanagement from Washington, D.C. does not win battles,” he said in a slightly veiled swipe at Obama. “They are won in the field drawing upon the judgment and expertise of wartime commanders and front line soldiers acting in real time — with real authority — and with a clear mission to defeat the enemy.”

Trump also sided with the generals with his order to “expand authority for American armed forces to target the terrorist and criminal networks that sow violence and chaos throughout Afghanistan.”

There is no denying Trump thinks highly of the military’s most decorated officers. He recently made another retired Marine four-star general, John Kelly, his White House chief of staff. Retired Army three-star Michael Flynn was his first national security adviser; he replaced him with an active duty Army lieutenant general: H.R. McMaster. Then there’s Defense Secretary James Mattis, the retired “leatherneck” whom Trump enjoys calling by his old military nickname: “Mad Dog.”

Amid ample signs of strain between the president and members of his own party, his Afghanistan decision is sure to — at least partially — please many hawkish Republican lawmakers.

One is Sen. Lindsey Graham, a senior Armed Services member, who after being briefed on Trump’s emerging plan in June said he was “very excited about” it.

“I’ve never been more proud of President Trump and his team than I am right now,” the South Carolina Republican said then.

Another is Armed Services Chairman John McCain, R-Ariz., who lambasted Obama for years over what the senator called the 44th commander in chief’s “don’t lose” Afghanistan strategy. McCain recently unveiled an amendment to the fiscal 2018 Pentagon policy bill that lays out a more aggresive approach to American’s strategy there.

“The goal of this strategy is to ensure that Afghanistan never again becomes a sanctuary for terrorists to plot and conduct attacks against America, our allies, or our interests,” McCain said earlier this month.

McCain’s amendment also would put pressure on Trump to put America’s resources where his mouth was on Monday night by giving the generals he sided with what they need. The Armed Services Committee chairman said the president should make sure “U.S. military commanders have all the necessary means … to carry out an integrated civil-military strategy.”

In his primetime speech, the president promised to do just that — and McCain was quick to voice his support.

“I commend President Trump for taking a big step in the right direction with the new strategy for Afghanistan,” McCain said in a statement released minutes after the president concluded his remarks. “The unfortunate truth is that this strategy is long overdue, and in the interim, the Taliban has made dangerous inroads. Nevertheless, I believe the president is now moving us well beyond the prior administration’s failed strategy of merely postponing defeat.”

McCain also praised Trump for his focus on a regional strategy — though the George W. Bush and Obama administrations used similar language. But Trump had strong words for Pakistan’s leaders.

“We can no longer be silent about Pakistan’s safe havens for terrorist organizations, the Taliban, and other groups that pose a threat to the region and beyond,” Trump said. “Pakistan has much to gain from partnering with our effort in Afghanistan. It has much to lose by continuing to harbor terrorists.”

Speaker Paul D. Ryan, R-Wis., just moments after the speech concluded, applauded the president’s refusal to lay out a timetable for withdrawing from Afghanistan, explained why he believes it is important the United States not telegraph its plans: “They will wait us out and then they will come back and fill that vacuum with terror.”

“I don’t think the Taliban will come to the table and reconcile in peace if they don’t think we are committed to seeing this through,” the speaker added.

Trump’s decision to take the advice of his generals — and lawmakers like McCain — brings ample risks, experts warn.

“In Korea we over-committed, and created a forever war. In Vietnam we did not, which culminated in a total defeat,” said Ryan Irwin, a world history professor at the University of Albany.

“My read is that Sen. McCain is still saying we should turn Afghanistan into Korea — all it’d take is commitment — and most everyone else is looking for a magic bullet to keep the Taliban at bay,” Irwin said.

[Graham ‘All In’ on Trump’s New Afghanistan Strategy]

Trump’s search for a solution to America’s nearly 16-year operation there comes at a time, after Obama drastically reduced the U.S. force commitment, where “we’re at crossroads” in the war-torn country, the Albany professor said.

It will take months — perhaps years — to determine whether the 45th commander in chief’s shift to a counterterrorism mission will be the long-elusive silver bullet that Obama and Bush found so elusive.

But according to Peter Brookes, deputy assistant secretary of Defense for Asian and Pacific affairs under Bush, Trump had to try. That’s because “Afghanistan remains unquestionably an extremist hot spot,” Brookes wrote recently.

“Afghanistan isn’t only a viper pit of violent Islamist extremism, but is a potential breeding ground for other terror groups with global aspirations and reach, too,” said the former Pentagon official. “As such, the United States and NATO need to play the long game in Afghanistan.”

Trump appears to have bought into such warnings from current and former officials like Brookes — and his cadre of generals.

On one hand, that is somewhat surprising, given at one point during the campaign he said this: “I know more about ISIS than the generals do. Believe me.”

But on the other, perhaps he signaled such a decision was possible, even likely, with this follow-on comment: “I love the generals.”

Lindsey McPherson and Niels Lesniewski contributed to this report.