"The loss of bin Laden and ... other key operatives puts the network on a path of decline that will be difficult to reverse," the State Department's report, "Country Reports on Terrorism 2011," released Tuesday, said. "These successes are attributable, in large part, to global counter-terrorism cooperation, which has put considerable pressure on the al-Qaida core leadership in Pakistan."
Despite the successes, "al-Qaida, its affiliates, and its adherents remain adaptable," the report said. "They have shown resilience; retain the capability to conduct regional and transnational attacks; and thus, constitute an enduring and serious threat to our national security."
Even as al-Qaida's core has weakened, affiliated groups around the world have been on the rise, the report said, noting al-Qaida in the Arabian Peninsula "represents a particularly serious threat."
The al-Qaida affiliate in Iraq shows signs of moving into Syria, where a civil war threatens the rule of President Bashar Assad, but Iraqi security forces have shown "substantial capability" in battling the group, the report said.
Despite counter-terrorism successes, al-Qaida and "violent extremist ideology and rhetoric" still spread in some parts of the world, the report said. The report noted that Boko Haram launched attacks across Nigeria, and several loosely knit militant groups have formed in the Sinai.
"Although there were no terrorist attacks in the United States in 2011, we remain concerned about threats to the homeland," the report said. "In the last several years, individuals who appear to have been trained by al-Qaida and its affiliates have operated within U.S. borders."
The report said Hamas and Hezbollah still play destabilizing roles in the Middle East. In Asia, groups such as Lashkar-e-Toiba, Tehrik-e Taliban Pakistan and the Haqqani network cite U.S. interests as legitimate targets for attacks.
While terrorism from al-Qaida affiliates and "state-sponsored terrorism originating in Iran" remain the top concerns for the United States, other forms of violent extremism threatened peace and security in 2011, the report said.
"The inability of any country to escape from terrorism," the report said, "was underscored in July in Norway, a country that has rarely been targeted in the past, when a lone right-wing extremist espousing a radical xenophobia carried out an attack that left more than 70 people dead and dozens more injured."