Despite some setbacks, al Qaeda’s core leadership in Pakistan remains the biggest threat to the United States, and the group continues to expand and strengthen worldwide, according to a new State Department report.

Last year, al Qaeda’s “core in Pakistan remained the most formidable terrorist organization targeting the U.S. homeland,” says the report, “Country Reports on Terrorism.”

“It has proven to be an adaptable and resilient terrorist group whose desire to attack the United States and U.S. interests abroad remains strong,” the report says.

The annual report covers the terrorism landscape in countries around the world and governments’ efforts to combat it.

Al Qaeda suffered leadership loses and faced pressure stemming from the Pakistani military campaign in the tribal areas, which limited the group’s ability to carry out spectacular attacks. However, according to the report, al Qaeda was “actively engaged in operational plotting” against the United States and continued to recruit, train and deploy operatives, including some from Western Europe and the United States.

Al Qaeda also sought to expand its operational capabilities by partnering with other terrorist groups worldwide, the report says.

The overall picture of terrorism last year underscores new threats in Somalia and Yemen, where insurgents have gained strongholds in vast, lawless areas.

Al Qaeda affiliates in Africa — including al Qaeda in the Islamic Maghreb and Al-Shabaab in Somalia — are among al Qaeda’s “most active” worldwide, the report says. Al-Shabaab, it says, presents a “serious terrorist threat to American and allied interests throughout the Horn of Africa.”

The report also says groups such as al Qaeda in the Islamic Maghreb and al Qaeda in the Arabian Peninsula pose a significant threat to U.S. interests. It cited Umar Farouk AbdulMutallab, who attempted to blow himself up while on a flight into Detroit, Michigan, and admitted that he was trained by the Arabian Peninsula group in Yemen.

(Read More: CNN)