In a major setback for al-Qaeda’s affiliate in East Africa, the Obama administration said Friday it had confirmed the death of a key Somali militant leader who had been targeted in an airstrike earlier in the week.

The White House and Pentagon released statements asserting U.S. responsibility for killing Ahmed Abdi Godane, the leader of al-Shabab, a Somali jihadist movement that has become an increasing threat to neighboring countries, including Kenya and Uganda. Godane had bragged of masterminding an audacious assault by gunmen on a Nairobi shopping mall last year, killing dozens while keeping local security forces at bay for days.

After receiving intelligence on the elusive Godane’s whereabouts, the U.S. military sent drones and other aircraft on Monday to an al-Shabab camp near the southern port of Barawe. They unloaded several Hellfire missiles and other munitions, flattening the camp and destroying a nearby vehicle. But with no U.S. troops on the ground to pick through the wreckage, Godane’s fate was not immediately clear.

The Pentagon did not reveal in its statement how it was able to confirm Godane’s death. A senior defense official, speaking on condition of anonymity because of the sensitivity of the issue, said the conclusion was drawn from “a series of indicators, based on intelligence” but declined to be more specific.

The U.S. military has occasionally carried out drone strikes and commando raids in Somalia, but not with the same frequency that the Pentagon and CIA have hunted suspected terrorists in Afghanistan, Pakistan or Yemen.

The mission to kill Godane came 11 months after Navy SEALs raided a seaside house in Barawe in an attempt to capture another al-Shabab leader. In that case, the commandos were forced to withdraw after a gunfight erupted, putting civilian bystanders at risk.

Monday’s drone strike in Somalia occurred even as Obama and his national security advisers have been preoccupied with what they describe as a bigger and more pressing terrorism threat: the emergence of Islamic State, a jihadist network that now controls large portions of Syria and Iraq.

On Friday, Obama cited Godane’s death as evidence that his deliberate and measured approach to confronting the networks is paying off, despite criticism from some lawmakers in Congress and even some allies that he has been too cautious.

“We have been very systematic and methodical in going after these kinds of organizations that may threaten U.S. personnel and the homeland,” Obama told reporters at the NATO summit in Wales. “But, have no doubt, we will continue and I will continue to do what is necessary to protect the American people.”

Under Godane’s direction, al-Shabab, which means “the youth” in Arabic, formally affiliated itself with al-Qaeda in 2012. The group had risen over the last decade to take control of much of Somalia, a chronically unstable country on the Horn of Africa. It has lost ground in recent years, however, beaten back by the intervention of African troops, many of them paid and trained by the U.S. government.

“Al-Shabab changed significantly under his leadership, including prioritizing a more global agenda while losing control of large swaths of territory within Somalia,” said Jon Temin, head of the Africa program at the U.S. Institute of Peace. “It is too soon to declare the demise of al-Shabab, but the group will now face difficult decisions about how to replace a brutal but effective leader.”

Counterterrorism officials said Godane had consolidated power within al-Shabab by eliminating several rivals, either by killing them or forcing them to go into hiding. As a result, they said it was unclear who might succeed him.

“He was a strong leader of al-Shabab and had taken care of rivals pretty effectively,” Matt Olsen, director of the National Counterterrorism Center, said during a briefing with reporters at the agency’s headquarters. Because of the leadership void and Godane’s role in personally shaping plots, Olsen said al-Shabab “may not be as active in carrying out attacks.”

Although Godane had sworn allegiance to al-Qaeda and his group has been a menace in East Africa, U.S. counterterrorism officials have been divided over how much of a direct threat al-Shabab poses to the United States.

The State Department had previously offered a $7 million reward for information leading to Godane’s arrest. It identified him as a 37-year-old native of northern Somalia who, among other aliases, went by the names Mukhtar Abu Zubeyr and Ahmed Abdi Aw Mohamed.

In a statement Friday, the White House said that Godane had “continued to oversee plots targeting Westerners, including U.S. persons, in East Africa,” but did not give further evidence of specific attempts to kill Americans.

Greg Miller contributed to this report.