By AAMER MADHANI, LOLITA C. BALDOR and ELLEN KNICKMEYE

WASHINGTON (AP) — President Joe Biden is about to announce his plans to withdraw remaining U.S. troops from Afghanistan, declaring that the Sept. 11 attacks “cannot explain” why American forces should still be there 20 years after the deadliest terror assault on the United States.

His plan is to pull out all the American forces — numbering 2,500 now — by this Sept. 11, according to U.S. officials. That is the anniversary of the attacks, which were coordinated from Afghanistan.

The U.S. cannot continue to pour resources into an intractable war and expect different results, Biden says in excerpts released ahead of an afternoon address in which he intends to detail his withdrawal timeline.

The drawdown would begin rather than conclude by May 1, which has been the deadline for full withdrawal under a peace agreement the Trump administration reached with the Taliban last year.

“We cannot continue the cycle of extending or expanding our military presence in Afghanistan hoping to create the ideal conditions for our withdrawal, expecting a different result,” Biden says in the speech excerpts. “I am now the fourth American president to preside over an American troop presence in Afghanistan. Two Republicans. Two Democrats. I will not pass this responsibility to a fifth.”

The decision marks perhaps the most significant foreign policy decision for Biden in the early going of his presidency.

He’s long been skeptical about the U.S. presence in Afghanistan. As Barack Obama’s vice president, Biden was a lonely voice in the administration who advised the 44th president to tilt towards a smaller counterterrorism role in the country while military advisers were urging a troop buildup to counter Taliban gains. Biden has also made clear he wants to recalibrate U.S. foreign policy to face bigger challenges posed by China and Russia.

Withdrawing all U.S. troops comes with clear risks. It could boost the Taliban’s effort to claw back power and undo gains toward democracy and women’s rights made over the past two decades. It also opens Biden to criticism, mostly Republicans and some Democrats, even though former President Donald Trump had also wanted a full withdrawal.

“A full withdrawal from Afghanistan is dumber than dirt and devilishly dangerous,” said Sen. Lindsey Graham, a South Carolina Republican. “President Biden will have, in essence, canceled an insurance policy against another 9/11.”

While Biden’s decision keeps U.S. forces in Afghanistan four months longer than initially planned, it sets a firm end to two decades of war that killed more than 2,200 U.S. troops, wounded 20,000, and cost as much as $1 trillion.

Biden says he consulted with allies, military leaders, lawmakers and Vice President Kamala Harris to help make his decision.

He is emphasizing that his administration will continue to support peace talks between the Afghan government and the Taliban and assist international efforts to train the Afghan military.

“It is time to end America’s longest war,” Biden says.

He also is trying to make the case that it is time to pay more attention to greater geopolitical challenges. In the early part of his presidency, Biden has spotlighted the growing economic competition with China and malign actions by Russia targeting the United States.

“Rather than return to war with the Taliban, we have to focus on the challenges that will determine our standing and reach today and into the years to come,” Biden says, according to the excerpts.

After his speech, Biden intends to visit Section 60 of Arlington National Cemetery to honor those who died in recent American conflicts.

A senior administration official said the September withdrawal date was an absolute deadline that won’t be affected by security conditions in Afghanistan.

The long conflict has largely crippled al-Qaida and led to the death of Osama bin Laden, the architect of the Sept. 11 attacks. But an American withdrawal also risks many of the gains made in democracy, women’s rights and governance, while ensuring that the Taliban, who provided al-Qaida’s haven, remain strong and in control of large swaths of the country.

As Biden prepared to lay out his plan, his top national security aides were consulting with NATO on Wednesday in Brussels to coordinate the alliance’s withdrawal from Afghanistan with the planned pullout of American troops.

Secretary of State Antony Blinken and Defense Secretary Lloyd Austin were meeting senior officials from the alliance’s 30 members to discuss NATO’s future presence in Afghanistan in light of the announcement of the U.S. withdrawal that Biden was to make later in the day.

Blinken said that he expected the allies to withdraw together but maintained that neither the U.S. nor NATO would abandon the country despite the impending pullout. There are roughly 7,000 NATO forces still in Afghanistan in addition to the remaining 2,500 U.S. troops.

“Together, we went into Afghanistan to deal with those who attacked us and to make sure that Afghanistan would not again become a haven for terrorists who might attack any of us,” Blinken said.

___ Knickmeyer reported from Oklahoma City. Associated Press writers Kathy Gannon in Islamabad , Matthew Lee in Brussels and Eric Tucker in Washington and broadcast correspondent Sagar Meghani contributed to this report.