It’s not just generals who are always prepared to fight the last war. President Biden’s April 14 announcement that U.S. forces will leave Afghanistan before the 20th anniversary of 9/11 has a long and complicated backstory. Biden said his decision will allow America to put this violent and ambiguous past behind it, to retire the frameworks that conditioned its foreign policy for a generation, and to focus its energies on the competition with China.

Perhaps so. The risk, however, is that Biden’s fixation on settling old scores has blinded him to contemporary realities, has prevented him from answering the question that will determine the future of both Afghan and U.S. security: Will the democratically elected government of Afghanistan survive American withdrawal?

Behind the official statements of Biden and Secretary of State Antony Blinken is the assumption that our exit (and that of our NATO allies) won’t jeopardize the existence of the regime based in Kabul. “While we will not stay involved in Afghanistan militarily,” Biden said, “our diplomatic and humanitarian work will continue.” Blinken echoed this sentiment at a press availability during his surprise visit to Kabul, when he said that “Even when our troops come home, our partnership with Afghanistan will continue.”

The robust promotion of civil society, counterterrorism, education for women and girls — none of this, we are told, will be interrupted when our soldiers leave. Nor will the enemy of civilization, the Taliban militia whose safe harbor for al-Qaeda was the reason for our intervention in 2001, abandon peace negotiations and impose its theocratic will through military force. “We have an expectation that the Taliban is going to abide by their commitments that they are not going to allow Afghanistan to become a pariah state,” Press Secretary Jen Psaki said the other day. “That’s our view.”

And a remarkably foolish view it is. You know the Taliban — always looking out for its international reputation. Of course there is no evidence that the Taliban has changed its methods, moderated its ideology, or abandoned its ambition to impose the strictest possible interpretation of shariah law on as many Afghans as it can reach. There is no evidence that the Taliban has ceased its attacks against Afghan security forces or that it has repudiated al Qaeda. Indeed, the very “intelligence community” on which Biden places so much importance says the Taliban will escalate its war on Kabul as soon as the last American is out and that “the Afghan government will struggle to hold the Taliban at bay if the coalition withdraws support.”

A big “if.” I do not doubt that — for a time — the aid will continue to flow to Afghan democrats, that weapons will continue to be supplied, and that some degree of overwatch from satellites and drones will continue to be provided. But I am equally certain that our attention will be redirected elsewhere, that neglect will lead to negligence, and that within a few years the Afghans may find themselves on their own. There is no substitute for the forward presence of U.S. forces, who are able to assess conditions on the ground, liaise with friends and neutrals, and deter bad actors of all sorts. On this point the Biden administration agrees with me — which is why, even as it announced the Afghanistan withdrawal, it deployed additional troops to Germany and conducted Freedom of Navigation Operations in the South China Sea.

Biden’s argument is that a U.S. military footprint is no longer required in Afghanistan, that we accomplished our main objectives years ago, that the costs of force protection for our remaining 2,500 soldiers outweigh the strategic and tactical benefits they provide, that “the threat has become more dispersed, metastasizing around the globe: al-Shabaab in Somalia; al Qaeda in the Arabian Peninsula, al-Nusra in Syria; ISIS attempting to create a caliphate in Syria and Iraq, and establishing affiliates in multiple countries in Africa and Asia.”

But Biden is unable to draw the causal connection between America’s involvement in Afghanistan and the “metastasizing” terrorist threat that emanates from places where religious fanatics operate more freely than they do in Afghanistan. Nor does he recognize that the terrorist groups he named in his address are based in exactly those locations where America has opted, for different reasons and to varying degrees, to pursue his policy of “offshore balance” rather than onshore residence. The existence of an allied host government is crucial to our ability to intercept, interrupt, interdict, and preempt terrorists before they strike. Biden’s decision to walk away from Afghanistan puts such a government at risk.

This danger is a fact Biden will not or cannot face. He is more interested in rectifying old errors than in preventing new ones. Both the location and the text of his address referenced the history of U.S. involvement in the Afghan theater. He delivered his remarks from the White House Treaty Room, where George W. Bush announced the launch of Operation Enduring Freedom on October 7, 2001, less than a month after al-Qaeda struck New York, Washington, and United Flight 93. He mentioned that he had called President Bush in advance of his directive. He recounted his visit to Afghanistan before becoming Barack Obama’s vice president and how it convinced him that the war was needless. “It has been well publicized and published that he opposed the surge back 10 years ago,” Psaki said. “And he was vocal about that in the appropriate manner at the time.”

That’s putting it mildly. Biden was furious. He was convinced that the Joint Chiefs of Staff and commanding generals had set the terms of the debate to guarantee that Obama would maintain and expand the war. His current determination to remove American troops over the objections of military commanders, including the Joint Chiefs chairman, General Mark Milley, is evidence of his desire to prove retroactively the wisdom of his position in 2009. His rejection of a conditions-based withdrawal underscores his disagreement with the generals. He dismisses the potential adverse consequences of our departure while implicitly conceding that conditions in Afghanistan are about to become worse.

Potentially much worse. It all depends on whether the Afghan government can fight the Taliban without the guidance of American troops. If it can’t, then over time Afghanistan will revert to the pre-October 2001 status quo of civil war, tribalism, and Taliban dominion. The forces of global jihad will feel empowered. That is what happened after the Soviet withdrawal from Afghanistan in 1989, from the American withdrawal from Somalia in 1993, from the American withdrawal from Iraq in 2011. Terrorism followed each retreat.

“I’m now the fourth United States president to preside over an American troop presence in Afghanistan: two Republicans, two Democrats,” Biden said. “I will not pass this responsibility on to a fifth.”

No, he won’t. What Biden will pass on instead is the responsibility for cleaning up his mess.

Matthew Continetti is a resident fellow at the American Enterprise Institute and the founding editor of The Washington Free Beacon. For more from the Free Beacon, sign up free of charge for the Morning Beacon email.