Speculation abounds as to who conducted today’s attacks in Oslo and for what reasons. For now, we don’t know who is responsible. Recent news has focused on the Nordic identity of the gunman in custody, suggesting that the incident was an example of domestic extremism.* At the same time, an organization called Ansar Al Jihad Al Alami, or The Helpers of the Global Jihad, has also taken responsibility for the attack. The group is a Kurdistan-based affiliate of Al Qaeda led by Abu Suleiman Al Nasser, someone who has repeatedly threatened attacks on Scandinavian countries, and most recently claimed responsibility for a defused bomb in Helsinki in June. Today, Al Nasser wrote that “Norway was targeted in order to become a lesson and example for the rest of the countries of Europe.” The attacks, he said, were a demand for “the European countries to withdraw their armies from the land of Afghanistan and to halt their war on Islam and Muslims.” He added, “We renew our warning again to the countries of Europe and we say to them, ‘Answer the demands of the Mujahideen, as what you see is only the beginning and what’s coming is more.’”

So, who, exactly is Al Nasser? Even before today’s events, he was a terrorist leader to be reckoned with. Calling himself the Minister of War for the Islamic State of Iraq, he essentially replaced Abu Ayyub Al Masri after he was killed in April 2010 in Iraq. (Al-Masri, at the time of his death, was the leader of the Al Qaeda offshoot in Iraq and had been close to Zarqawi, as well as to Ayman Zawahiri, now the first leader of Al Qaeda after bin Laden’s death.) Al-Nasser has been outspoken in his anger and his intent to do violence in Europe for over a year. Via his blog, he has threatened harm against those countries that participated alongside the U.S. in the war in Iraq. He has warned, as well, that a suicide bombing in Sweden in December 2010 was but the beginning of bloodshed in Scandinavian countries in retribution for helping militarily in Iraq. Finland, Denmark, and Sweden have individually been the targets of his vitriol and his call to violence. He has urged the use of guns, the assassination of government leaders, and the threat of continuous bloodshed in his online statements.

Al Qaeda may today be like the hydra where when you cut off one head, several grow back. Whether it’s the American Al Qaeda member Anwar Al Awlaki, or Al Nasser in Iraq, or Zawahiri himself, those in leadership positions from Somalia to Yemen to Iraq are now making themselves known as individuals to contend with, whose calls to violence are at the very least a cause for concern. Speculation before bin Laden’s death—apparently verified by what was found on his computer—suggests that he very much remained the point person of Al Qaeda in its many guises until the very end. As a result, a counterterrorism focus on Al Qaeda central made good sense. Now, perhaps our focus will need to shift. If today’s attacks were in fact the work of Al Nasser, they suggest that the post-bin Laden world is quite different than the era of bin Laden—and its violence not necessarily any easier to contain.

*UPDATE: After this article was published, Norway identified the suspect in custody as Anders Behring Breivik, who is "right-wing and a Christian fundamentalist." He has not been linked to any jihadist groups; authorities do not yet know, if Breivik is indeed the perpetrator, whether he was part of a larger conspiracy or acted alone. 

Karen J. Greenberg is the executive director of the Center on Law and Security at New York University.