“If the martyrdom of Zawahiri is confirmed, then shame on you that we could not protect the true hero of Islam,” an Afghan named Ehsanullah tweeted in response to a statement early Tuesday by the chief Taliban spokesman that the al-Qaeda leader was killed in a U.S. drone strike.

The assassination of Zawahiri, a hero to Islamist militant groups but a long-wanted terrorist in the West, has also crystallized the ongoing struggle between moderate and hard-line factions within the Taliban regime. Several leaders of the hard-line Haqqani network, long denounced by U.S. officials for directing high-profile terrorist attacks, hold powerful positions in the regime.

Now, some Afghan and American analysts said, the drone strike may harden Taliban attitudes and push the regime toward an open embrace of the extremist forces it pledged to renounce in its 2020 peace deal with the United States.

“The Taliban are in deep political trouble now, and they are going to face pressure to retaliate. The relationship they have with al-Qaeda and other jihadi groups remains very strong,” said Asfandyar Mir, an expert on Islamic extremism at the U.S. Institute of Peace in Washington. “I think we should brace for impact.”

Mir noted that while Taliban officials have been hoping to gain international recognition and access to $7 billion in assets that were frozen by the Biden administration, the group’s supreme religious leader, Hibatullah Akhundzada, declared flatly at a national conclave in May, “We are in a clash of civilizations with the West.”

There is deep-seated animosity here toward the United States, which intensified after U.S. troops withdrew last year and the war economy collapsed, leaving millions of Afghans jobless. When Afghan officials belatedly confirmed that a U.S. drone had killed the al-Qaeda leader, after first insisting the strike was a harmless rocket attack, many Afghans were infuriated.

“We have so many worries already. For a whole year, there have been no jobs, no business, no activity. But at least the fighting was over. The Taliban was in charge, and there was good security,” said a resident of the Sherpur neighborhood, where the drone struck, who gave his name as Hakimullah. “Now, suddenly, this attack happens, and everyone is frightened again.”

Many Afghans seem to know little about Zawahiri or al-Qaeda. In part, this is because so many of them were born after the Sept. 11, 2001, attacks planned and carried out by al-Qaeda, and in part because the al-Qaeda fighters who joined forces with the Taliban are Middle Easterners whose presence in Afghanistan has always been low profile.

Until now, people here were far more focused on the threat posed by a different Sunni Muslim extremist movement, known as the Islamic State-Khorasan or ISIS-K. The group has in the past repeatedly bombed mosques, schools and other sites in Kabul, especially during the Shiite Muslim festival of Muharram, which began this week.

Taliban Interior Minister Siraj Haqqani denied that al-Qaeda maintains a presence in Afghanistan and claimed that the government would not allow such groups to operate in the country. Speaking in an interview Tuesday night with an Indian television station, he vowed that the Taliban would continue to battle the Islamic State.

Among those most dismayed by the turn of events are Afghan civilians who have tried to form working relationships with the new Taliban authorities, encouraging them to develop moderate and practical governing policies rather than focusing exclusively on religion.

Faiz Zaland, who teaches governance and political science at Kabul University, expressed frustration with the Taliban for failing to anticipate the risks of bringing Zawahiri to the capital and concern that the U.S. attack had doomed chances for the moderate elements in the regime to compete with the hard-line religious figures at the top.

“The Taliban are stuck now, and it’s their own fault,” he said. “This is going to undercut the achievements of their first year, and people who care feel betrayed and scared.”

Haq Nawaz Khan in Peshawar, Pakistan, contributed to this report.

At the same time, the Taliban insisted that there is “no threat to any country, including America, from the soil of Afghanistan.” It said the Afghan government wants to “implement the Doha pact,” a peace agreement in 2020 between U.S. and Taliban officials that included a Taliban pledge not to harbor extremist groups such as al-Qaeda.

The statement also said that Taliban leaders have ordered several investigative agencies to “conduct a comprehensive and serious investigation” into the incident.

The statement was issued after senior Taliban figures reportedly held high-level meetings to decide how to respond to the drone strike. By saying it was unaware of Zawahiri’s “arrival or stay” in the capital, the Taliban seemed to be issuing a broader denial of its ties with al-Qaeda in general. U.S. and U.N. intelligence assessments have said those ties are strong and ongoing.

The Taliban’s claim that it had no knowledge of Zawahiri’s presence drew immediate skepticism. “It beggars belief that Zawahiri could live where he did for as long as he did and without the Taliban knowing,” said Michael Kugelman, an expert on the region at the Wilson Center in Washington. “Perhaps not all Taliban knew, but some Taliban must have known.”

Administration officials in Washington have described a painstaking, months-long surveillance effort that preceded the drone strike, in part to ensure that the target was correct and in part to prevent civilian casualties. The house where Zawahiri was reported killed is in an upscale urban district with large mansions built close to each other.

The official denial of Zawahiri’s presence seemed aimed in part at saving face after the humiliation of being unable to protect a senior guest and at lowering tensions with the United States despite the statement’s pro forma condemnation.

The Taliban, facing a humanitarian and economic crisis across the country, is desperate to win international recognition and gain access to some $7 billion in Afghan funds frozen by the Biden administration.

In addition, Zawahiri’s death raises an awkward internal religious issue for the Taliban because of Muslim customs requiring quick burials and large formal funerals for dignitaries. Although Zawahiri did not wield as much authority in al-Qaeda as his predecessor, Osama bin Laden, his relations with the Taliban were old and deep.

In the past several days, many experts have said the embarrassment of the drone strike might drive the Taliban toward a more hard-line posture and even a closer relationship with al-Qaeda and other extremist groups, despite its pledge in the Doha agreement to renounce them.

“The Zawahiri killing, perpetrated by a unilateral U.S. military action, has embarrassed the Taliban and exploded their myth that they don’t have ties to al-Qaeda,” said Kugelman, deputy director of the Wilson Center’s Asia program.

“If they stay quiet about the raid and don’t take a confrontational position toward the U.S., they risk antagonizing their rank and file and alienating militant allies,” Kugelman said. “The Taliban can’t afford those outcomes at a moment when they’re already struggling to consolidate domestic legitimacy and manage an acute economic crisis.”

When U.S. forces withdrew from Afghanistan last August, Biden administration officials said they would retain capability for “over-the-horizon” attacks from elsewhere on terrorist forces inside Afghanistan. The attack against Zawahiri is the first known counterterrorism strike there since the withdrawal.

Speaking in a live television address from a balcony at the White House, Biden announced that days ago he had authorized a strike to kill Zawahiri. “Justice has been delivered, and this terrorist leader is no more,” Biden said.

The strike occurred at 9:48 p.m. Eastern time on Saturday, according to a senior administration official who briefed reporters on the operation. A drone fired two Hellfire missiles at Zawahiri as he stepped onto the balcony of a safe house in Kabul, where he had been living with members of his family, the official said.

A loud blast was heard in the Shirpur neighborhood in central Kabul. The district, long a derelict area owned by the Afghan Defense Ministry, was converted into an exclusive residential area of large houses in recent years, with senior Afghan officials and wealthy individuals owning mansions there.

A few blocks away from the site, residents and shopkeepers spoke openly Tuesday morning about hearing the powerful blast. Some said they had been frightened by the roar and the ground shaking, while others said they had long been accustomed to such attacks during years of war.

“All the children ran away from the sound. We hadn’t heard anything like it since the old government was in charge,” said Haq Asghar, a retired army officer chatting outside a hardware shop. He said that Shirpur was tightly controlled by the Taliban, and that anyone occupying a house or shop had to provide detailed documents and information.

“Security is very good now. They definitely don’t let strangers settle in here,” he said.

Shirpur is divided between an older section of modest homes and shops, which is open to traffic, and a high-security section of ornate modern mansions, which is heavily guarded and closed to traffic. The house reportedly occupied by Zawahiri and his family appeared to be located in the secure section, behind a large bank and several guarded alleys lined with government compounds.

The intelligence community had tracked Zawahiri to the safe house and spent months confirming his identity and developing a “pattern of life,” tracking his movements and behavior, the official said. Intelligence personnel also constructed a model of the safe house, which was used to brief Biden on how a strike could be carried out in such a way that it lessened the chances of killing any other occupants or civilians, the official said, adding that intelligence agencies have concluded that Zawahiri was the only person killed in the strike.

“The United States continues to demonstrate its resolve and capacity to defend Americans from those who seek to do it harm,” Biden said, making it “clear again [that] no matter how long it takes, no matter how you hide … the United States will find you and seek you out.”

Senior administration national security officials were briefed in early April on the information that Zawahiri was believed to be living in the house, which he never left, the official said.

Biden received updates throughout May and June, and on July 1, he was briefed in the White House Situation Room by key Cabinet members and advisers, including CIA Director William J. Burns, Director of National Intelligence Avril Haines, National Counterterrorism Center Director Christine Abizaid and national security adviser Jake Sullivan, the official said.

The president met again with his top advisers on July 25 and continued to press the intelligence agencies on how they planned to conduct a strike with minimal civilian casualties, the official said. All his advisers “strongly recommended” the strike, which Biden then authorized, the official said.

Senior members of the Haqqani Taliban faction were also aware that Zawahiri was living in the house and took steps after the strike to conceal his presence, the official said, calling the terrorist leader’s presence in Kabul a violation of the Doha Agreement signed between the United States and the Taliban in 2020.

The agreement leading to the U.S. withdrawal from Afghanistan included a Taliban pledge not to allow terrorist groups with international aims to operate within their territory and to break all relations with those groups. While the Islamic State has been growing within Afghanistan and has claimed frequent attacks against the Taliban and civilian targets, al-Qaeda appears to retain a strong relationship with the Taliban government.

Zabihullah Mujahid, the chief Taliban spokesman, confirmed the drone strike early Tuesday, saying it had been “carried out by US unmanned planes” and had “struck a residential house in the Shirpur area of Kabul.”

In Shirpur on Tuesday morning, many people were confused about the source of the strike, which Taliban authorities initially had called a rocket attack that had not injured or killed anyone. Some blamed it on next-door Pakistan, and others had heard rumors that the Americans were behind it. But only a handful knew the strike had been announced by Biden in Washington.

“I heard Joe Biden did it,” said a man named Abdul Wali, who was changing money at a sidewalk stand. “This means Afghanistan still belongs to America. They can do whatever they want. If they can do a drone strike in the city, it means they are still in charge.”

Nobody in the community was willing to express an opinion about al-Qaeda, but several said they were concerned that the attack would spark a new round of violence.

“We have had so many years of war, and things were just beginning to settle down,” said Syed Agha, a jobless schoolteacher selling vegetables from a cart. “The conflict is past, and no one should have the right to violate our sovereignty. An attack like this could badly affect our future.”

In a tweet and an online statement in Afghan Pashto, Mujahid said the Taliban government “strongly condemned the attack,” terming it a “violation of international norms and the Doha peace deal.”

Zawahiri, whose face was familiar to millions of Americans from his videotaped diatribes against the United States, played an important role in turning al-Qaeda into a more lethal and ambitious terrorism organization, according to many of the investigators who hunted its leadership for decades. By merging his Egyptian-centric organization with bin Laden’s, the group became a far more dangerous and global terrorism group, analysts said. Zawahiri was indicted on a charge of the bombings of U.S. embassies in Kenya and Tanzania in 1998, attacks that first highlighted the growing threat from al-Qaeda.

Both bin Laden and Zawahiri escaped U.S. forces in Afghanistan in late 2001 after the 9/11 attacks, and Zawahiri’s whereabouts had long been a mystery. Bin Laden was killed in a raid by U.S. forces in Pakistan in 2011.

After bin Laden’s death, Zawahiri became the figurehead leader of al-Qaeda, but he was a hunted man in charge of a decimated organization. Lacking bin Laden’s loyal following, Zawahiri tried to command far-flung terrorist groups that often ignored his decrees and rejected his advice. In particular, he was overshadowed by the rise of the Islamic State and its bloody dominion for several years over parts of Syria and Iraq.

But with much of the group’s original leadership captured or killed, Zawahiri was perhaps the most visible reminder of al-Qaeda’s grim legacy.

“I just got chills up and down my spine,” said Charles G. Wolf, whose wife was killed at the World Trade Center in the terrorist attacks, when he learned about the U.S. strike. “It’s great to hear … I’m sure there will be someone else to step in his shoes, but I think it sends a signal that we are still going after terrorists regardless of politics.”

In a report issued last month, U.N. analysts said Zawahiri had been “confirmed to be alive and communicating freely,” with “regular video messages that provided almost current proof of life.” It noted that his “increased comfort and ability to communicate” coincided with last year’s Taliban takeover of Afghanistan.

“Al-Qaeda is not viewed as posing an immediate international threat from its safe haven in Afghanistan because it lacks an external operational capability” from there, “and does not currently wish to cause the Taliban international difficulty or embarrassment,” the report said.

Both the United Nations and the U.S. intelligence community have assessed that the operational threat from al-Qaeda is now centered in its African and Middle East affiliates. “Al-Qaeda probably will gauge its ability to operate in Afghanistan under Taliban restrictions and will focus on maintaining its safe haven before seeking to conduct or support external operations from Afghanistan,” the Office of the Director of National Intelligence assessed this year.

A former member of al-Qaeda who later joined the Islamic State downplayed the significance of Zawahiri’s death, noting that he was barely visible in recent years.

“I’m sure Biden will try to make it sound as if it’s something big, but actually it’s not significant for us at all,” said the member of the Islamic State who spoke on the condition of anonymity to discuss the al-Qaeda leader. “Ayman al-Zawahiri became the emir after bin Laden, and now he is a shaheed [martyr]. And that’s it for us. The significant question will be: Who will become the new leader now?”

In the wake of the strike on Zawahiri, the senior official said the administration warned the Taliban not to take any steps that would harm Mark Frerichs, a 60-year-old American civil engineer and Navy veteran who was kidnapped in Afghanistan in January 2020. The only known remaining American hostage in Afghanistan, he is believed to have been captured by the Haqqani network, a Taliban faction that during the Afghanistan war was based in Khost province, near the Pakistan border, and in Pakistan itself. Its leader, Sirajuddin Haqqani, is now interior minister in the Taliban government in Kabul.

The Taliban has denied any knowledge of Frerichs’s whereabouts. The director of a contracting company called International Logistical Support, he had traveled to Afghanistan numerous times during the U.S. military presence there. In May 2020, the FBI offered a $1 million reward for information leading to his release or rescue.

In April, the New Yorker published information from what it said was a video from a source who could not be verified, showing Frerichs pleading for his release. In it, he states that it was being recorded on Nov. 28, 2021. The magazine said Frerichs’s sister had confirmed that it was her brother.

Frerichs’s family has criticized both the Trump and Biden administrations, the former for signing a peace deal with the Taliban that did not mention him and the latter for implementing it.

Constable reported from Kabul. Ellen Nakashima, Devlin Barrett and Olivier Knox in Washington contributed to this report.