Editor's Note: This piece originally appeared in Foreign Policy.

The killing of Nasir al-Wuhayshi, reportedly via U.S. drone strike, is not just another notch in the belt of America’s long campaign against al-Qaida and its allies. Wuhayshi was one of al-Qaida’s top remaining leaders, and he is the highest-level death the organization has suffered since Osama bin Laden was killed in 2011. Wuhayshi headed al-Qaida’s most active affiliate, the Yemen-based al-Qaida in the Arabian Peninsula (AQAP), and was the designated successor of al-Qaida leader Ayman al-Zawahiri. His killing adds one more element of uncertainty to the turbulence in Yemen and may set AQAP on a new path. Which path, however, remains an open question.

Wuhayshi helped transform AQAP from a fractious organization on the edge of defeat to one that menaces both Yemen and the United States. A decade ago, Yemen’s jihadi movement seemed near defeat. In the aftermath of 9/11, the Yemeni government rounded up jihadis and imprisoned Wuhayshi, and it was Saudi Arabia, not Yemen, that was the focus of jihadis in the Arabian Peninsula. In 2003, al-Qaida sponsored the original AQAP’s uprising against the Saudi government. Several years later, most of AQAP’s Saudi members were dead or in jail, and its remnants had fled to Yemen. There, they mixed with Yemeni jihadis, including important figures like Wuhayshi, who had escaped from Yemen’s jails in 2006. In 2009, two regional Islamist groups merged and formally anointed themselves AQAP, basing their operations in Yemen and trying to unseat the government. As Osama bin Laden’s former secretary, Wuhayshi became the group’s leader and embraced al-Qaida’s emphasis on attacking Western targets.

The group made fitful progress, at times taking territory but often losing it quickly after alienating locals and proving vulnerable to government counterattacks. But when the government of Yemeni President Ali Abdullah Saleh fell in 2012 during the Arab Spring, AQAP tried to step into the void. Saleh’s successor, Abed Rabbo Mansour Hadi, pursued AQAP vigorously, but his weak government was unable to score any lasting successes.

In addition to its prowess in Yemen, AQAP has long been al-Qaida’s most active affiliate when it comes to taking on the West. The organization was behind the 2009 Christmas Day attempt to down a U.S. airliner over Detroit, a near-miss only foiled by the bomber’s incompetence and the quick thinking of the plane’s passengers. AQAP tried again in 2010, this time attempting to down U.S. cargo planes. The organization also attacked Western targets in Yemen, and puts out Inspire, a stylish English-language online publication that is one of al-Qaida’s more effective attempts to influence Western jihadis.

These AQAP efforts to attack the United States and the West, in general, led to a greater U.S. focus on Yemen and more drone attacks there. In 2011, the United States killed Anwar al-Awlaki, a U.S. citizen and AQAP member who helped lead the terrorist group’s campaign against targets in the United States and Europe. Awlaki has continued to inspire terrorists after his death, with Boston Marathon plotters downloading his sermons before their attack. Awlaki also inspired the Fort Hood shooter in 2009 and the attacks on the Charlie Hebdo office in 2015.

Wuhayshi’s death, however, comes as Yemen is falling apart. Earlier this year, Hadi’s government fell to the Houthi rebels, Yemeni Shiites who oppose both Yemen’s traditional order and the Sunni fanatics of AQAP who see Shiites as apostates. Alarmed by Houthi ties to Iran, Saudi Arabia has led an intervention in Yemen on Hadi’s behalf, bombing the Houthis and trying to reverse their gains. AQAP seems to be flourishing amid the chaos, as its enemies turn on one another.

But with Wuhayshi’s death, AQAP may find it difficult to further exploit the Yemeni civil war. Personal connections, reputation, and charisma play a bigger role in leadership in the jihadi cause than do formal rank, and it is not clear if Qasim al-Raimi, the designated new leader, can retain the support of the AQAP rank and file. There is always a chance, of course, that Raimi proves an even more effective leader than Wuhayshi, and some observers see him as “more dangerous and aggressive.” (Lest we forget: In 1992, the Israelis killed Hezbollah’s Secretary-General Abbas al-Musawi, one of the group’s most competent leaders. Musawi was replaced by Hassan Nasrallah, who has proven one of the most effective terrorist and guerrilla leaders in modern times.)

The bad news is that Raimi and AQAP may seek revenge, both out of genuine anger and to score points within the jihadi community. Al-Qaida’s chief bomb-maker, Ibrahim al-Asiri, may still be out there and has likely passed his sophisticated techniques on to others in Yemen.

The bad news is that Raimi and AQAP may seek revenge, both out of genuine anger and to score points within the jihadi community.

Over time, however, Wuhayshi’s death may push AQAP to focus even more on Yemen and less on the West. His close, personal ties to the al-Qaidacore may have been part of why AQAP was a steadfast ally of Zawahiri in his power struggle with the Islamic State. The opportunities and risks in the civil war are both tempting and frightening for AQAP. On the one hand, by taking up arms against the hated Shiites, AQAP can position itself as the defender of Yemen’s Sunnis, a strategy that has worked well for the Islamic State in Iraq and Syria. AQAP might gain more recruits and local support, while drawing foreign fighters and money from Sunnis eager to find yet another Shiite-Iran axis to oppose. Not surprisingly, AQAP has stepped up its operations against the Houthis in recent months.

AQAP also has an opportunity to govern. And the bad news for the West is that it has learned from its own many mistakes on this front. In the past when AQAP made gains, it tried to impose a strict version of Islamic law that alienated local communities. Now when its fighters seize territory, theywork with local tribal figures and other elites, avoiding the most controversial measures and trying to portray themselves as guardians, not overlords.

Wuhayshi’s death also comes at a time when the broader jihadi movement is split between backers of al-Qaida and supporters of the Islamic State, a struggle in which AQAP has long played an important role. As al-Qaida’s most active anti-Western affiliate, AQAP was important to Zawahiri’s claim that he was leading the struggle against the United States. Its strength in Yemen, moreover, also expanded al-Qaida’s presence and prestige to an important part of the Arab world. Islamic State supporters have already conducted attacks in Yemen, and the death of Wuhayshi offers them a chance to expand their influence there. The core leadership of AQAP is not likely to join the Islamic State, but some of its cells and supporters could break off if Raimi proves a weak leader.

For now, Wuhayshi’s death means the United States has another point in the struggle against the jihadi movement. In the long term, successful disruption is more likely if the United States and its allies can keep the pressure on AQAP, forcing its leaders to go on the run and hindering their ability to communicate — particularly difficult challenges for a group in transition under new leadership. Wuhayshi’s death also comes on the heels of the deaths of several other AQAP members, including its top ideologue and spokesman. Having to hide also makes it difficult for the group to govern, as its exposed leaders run the risk of being killed. But AQAP has lost many leaders before, yet remains a force to be reckoned with. So at best, this should be seen as winning a battle, not the war.