KABUL, Afghanistan — The U.S. drone strike that killed al-Qaida leader Ayman al-Zawahri here early Sunday morning also struck a humiliating blow to the Taliban regime, which had secretly hosted the aging extremist in the heart of the Afghan capital for months but failed to keep him safe.

Just as the Taliban was preparing to celebrate its first year in power later this month, the attack has sparked a nationalistic backlash against the beleaguered regime at home and taunting comments on social media calling for revenge against the United States.

"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-Qaida leader had been killed in a U.S. drone strike.

The assassination of al-Zawahri, 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.

In a pair of tweets Tuesday night, Anas Haqqani, an influential Taliban figure who participated in the Doha peace negotiations, said, "This attack by the United States is a barbaric act, and it will have serious implications." The second tweet showed a video of U.S. forces under attack and said it was "dedicated to the president of the savages. I think the US has forgotten past experiences."

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-Qaida 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-Qaida 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 al-Zawahri or al-Qaida. In part, this is because so many of them were born after the Sept. 11, 2001, attacks that U.S. officials said were masterminded by al-Zawahri and his associates, and in part because the al-Qaida 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.

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 al-Zawahri 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."