WASHINGTON — After nearly 20 years of an American armed presence in Afghanistan, President Joe Biden has ordered the withdrawal of all U.S. military forces there, in effect acknowledging failure of the long mission that had plagued the three previous presidents and NATO allies.

Biden announced from the White House on Wednesday that the remaining 2,500 U.S. troops and 1,000 special forces will leave by Sept. 11, four months after a deadline agreed to with the Taliban. More than 2,300 American soldiers have died in Afghanistan since the initial deployment in 2001, following the terrorist attacks on New York and Washington on September 11.

By way of dramatizing the significance of his action, the president went to nearby Arlington National Cemetery and placed a memorial wreath near the graves of thousands of American forces buried there.

While there, accompanying reporters asked him what he thought, viewing all the rows of crosses. He told them: “I’m always amazed at generation after generation, the women and men prepared to give their lives for their country.” On a personal note, he added, “I have trouble these days ever showing up at a cemetery not thinking of my son Beau, who proudly insisted on putting on that uniform and going with his unit to Iraq.”

From the Treaty Room at the White House. Biden solemnly said, “I’ve concluded that it’s time end to end America’s longest war.” Noting he is the fourth president — two from each party — to preside over it, he declared, “It’s time for American troops to come home,” and that “I will not pass this responsibility to a fifth.”

To those who question his timing, Biden said: “The main argument for staying longer is what each of my three predecessors have grappled with: No one wants to say we should be in Afghanistan forever, but they insist now is not the right moment to leave.”

He continued: “We went to Afghanistan because of a horrific attack that happened 20 years ago. That cannot explain why we should remain there in 2021. Rather than return to war with the Taliban, we have to focus on the challenges that are in front of us” elsewhere.

Biden may have had in mind new sanctions he imposed against Russia the next day for its extensive hacking operation that breached U.S. government agencies and private corporations, even as he proposed a summit with Vladimir Putin in Europe this summer to pursue better relations between the two superpowers.

As for the Afghanistan withdrawal, Biden reiterated that “we cannot continue the cycle of extending or expanding our military presence in Afghanistan, hoping to create ideal conditions for the withdrawal and expecting a different result. ... We gave that argument a decade. It never proved effective. Not when we had 98,000 troops in Afghanistan, not when we were down to a few thousand. Our diplomacy does not hinge on having boots in harm’s way.”

At the same time, Secretary of State Antony Blinken and Secretary of Defense Lloyd Austin in Brussels met with NATO leaders who said they too would start pulling out of Afghanistan by May 1. Blinken told them “the United States will never forget the solidarity that our NATO allies have shown every step of the way. No country could have achieved what we achieved as an alliance, working together.”

Such observations signaled Biden’s reassurance that in his opening focus on coping with the coronavirus pandemic and the resulting economic lockdown at home, he will not ignore his leadership obligations abroad.

In terms of history, his decision to end America’s “endless war” in his first months in the Oval Office almost certainly will stand as a milestone, whatever else ensues in the Biden presidency.

Jules Witcover’s latest book is “The American Vice Presidency: From Irrelevance to Power,” published by Smithsonian Books. You can respond to this column at juleswitcover@comcast.net.

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