Nasir al-Wuhayshi, leader of al-Qaeda’s branch in Yemen, was killed in a CIA drone strike last week. He also had been designated second in command of al-Qaeda’s global network. (Reuters)

In separate strikes last week on veteran al-Qaeda leaders, the United States demonstrated again the extent to which it has perfected an almost eerie capability to find the world’s most wanted terrorism suspects in some of the world’s most chaotic environments and deliver lethal blows from above.

But the continued spread of al-Qaeda’s ideology and the emergence of brutal new offshoots, including the Islamic State, have underscored the limitations of a U.S. strategy that remains largely reliant on “decapitation” strikes.

U.S. officials confirmed Tuesday that Nasir al-Wuhayshi, leader of al-Qaeda’s affiliate in Yemen, was killed last week by a missile fired from a CIA drone. The announcement came one day after U.S. military officials said that a former al-Qaeda operative in Libya appeared to have been killed in a bombing Saturday by U.S. fighter jets.

Obama administration officials touted the potential impact of the operations. White House spokesman Ned Price said that Wuhayshi’s death “removes from the battlefield an experienced terrorist leader and brings us closer to degrading and ultimately defeating these groups.”

How much closer, however, remains unclear. Many officials and experts in the U.S. counterterrorism community now see the destruction of al-Qaeda and its progeny as a more distant goal than at any time since the Sept. 11, 2001, attacks.

Islamist terrorist groups have taken advantage of political turmoil in the Middle East to make gains in recruitment, territory and influence. The locations of the latest U.S. strikes, Yemen and Libya, are countries where the collapse of central governments has enabled radical Islamist elements to flourish.

Even with no presence or partners on the ground in those places, the United States has managed to maintain its lethal reach. But in a measure of how the expectations that follow such operations have shifted, U.S. officials and experts said the strikes may prove to be as advantageous to ascendant groups such as the Islamic State as they are damaging to al-Qaeda.

“The decapitation campaign of AQ senior leadership has left the group with diminishing capabilities to drive the global terrorist movement and to threaten the West as they once did,” said Juan Zarate, a former senior counterterrorism adviser to President George W. Bush.

But the latest U.S. operations “have little relevance to what ISIS is building and growing in the heart of the Middle East,” Zarate said, using an alternative term for the Islamic State, “and may actually strengthen their hand in Yemen, Saudi Arabia and Libya.”

The targets last week were members of a dwindling generation of militants with links to al-Qaeda’s founders.

Wuhayshi once served as a senior aide to Osama bin Laden and escaped from a Yemeni prison in 2006 to form an al-Qaeda franchise that eventually eclipsed its parent organization as a threat to the United States. Al-Qaeda in the Arabian Peninsula (AQAP) has been linked to plots including the attempted bombing of a ­Detroit-bound plane in 2009 and the attacks on the Charlie Hebdo satirical newspaper in Paris this year.

Mokhtar Belmokhtar, targeted in Libya, was a former member of al-Qaeda in the Islamic Maghreb, the network’s North African affiliate, but formed a breakaway group in 2012. The following year, he staged a bloody siege of a gas complex in eastern Algeria that killed 40 people, including three Americans.

Both men were seen as drivers of their respective terrorist groups’ anti-Western agendas, and Wuhayshi had been designated al-Qaeda’s second in command, meaning he would have led the global network if Ayman al-Zawahiri, bin Laden’s successor, were captured or killed.

The attacks extend a remarkable U.S. record against high-
value al-Qaeda targets, a run that extends back to the killing of Abu Musab al-Zarqawi in Iraq in 2006 and includes the deaths of bin Laden and Anwar al-Awlaki — a U.S. citizen who became a senior operative for AQAP — in 2011.

All were seen as potentially staggering blows to terrorist organizations that nevertheless managed to regroup — although al-Qaeda’s core in Pakistan remains significantly weakened.

Bruce Riedel, a former CIA analyst and terrorism expert at the Brookings Institution, said Islamist groups have been able to turn to a new generation of leaders, many of whom rose through their organizations’ ranks without surfacing on U.S. target lists.

“Look at Baghdadi,” Riedel said, referring to Abu Bakr al-Baghdadi, the leader of the Islamic State, which has seized territory across Iraq and Syria and declared itself a caliphate. “Nobody knew who Baghdadi was two or three years ago. But clearly people on the inside in Iraq knew.”

U.S. officials said Wuhayshi’s subordinates in AQAP — including his apparent successor, Qassim al-Raimi — are seen as committed to al-Qaeda and unlikely to shift the organization’s course or pursue an affiliation with the Islamic State.

But in interviews Tuesday, Yemeni citizens in the district where Wuhayshi was killed said there have been growing indications of Islamic State activity in the region, and they voiced concern that the group, also known as Daesh, might now be emboldened.

“There’s more concern now about Daesh,” said Salem al-Hamoomi, a radio journalist in Mukalla, a city in southern Yemen near where Wuhayshi was killed. “People fear its ideology, and people fear the group is here.”

Seth Jones, a terrorism analyst at the Rand Corp., said that Wuhayshi’s death should “be viewed in the context of the struggle between al-Qaeda and the Islamic State over the leadership of the broader Salafi-Jihadi movement.” Even before the AQAP leader’s demise, Jones said, the Islamic State had “co-opted a few small, local jihadist networks in Yemen.”

The Obama administration’s dependence on drone surveillance and airstrikes against al-Qaeda and other terrorist groups reflects, in part, a reluctance to be drawn more directly into Middle East conflicts. But the policy has also been driven by developments that derailed administration attempts to build a new counterterrorism strategy around providing support to regional partners.

The collapse of the U.S.-backed government in Yemen this year forced the CIA and the U.S. military to pull out dozens of officers who had worked closely with Yemeni security agencies on counterterrorism operations. The Yemeni government was ­effectively deposed by Shiite rebels known as Houthis who are antagonistic toward the United States as well as the largely Sunni membership of al-Qaeda.

Rep. Adam B. Schiff (Calif.), the ranking Democrat on the House Intelligence Committee, said that AQAP’s efforts to take advantage of the turmoil and fend off advances by the Houthis may have made its leadership more vulnerable to U.S. intelligence-gathering.

“The disintegration of Yemen has just been utterly catastrophic in terms of letting al-Qaeda out of the box,” Schiff said. “There’s no question our intelligence has suffered. But there are residual intelligence capabilities that are still potent.”

Hugh Naylor in Beirut and Ali al-Mujahed in Sanaa, Yemen, contributed to this report.