The Obama administration has significantly increased the frequency of drone strikes and other air attacks against the al-Qaeda affiliate in Yemen in recent months amid rising concern about political collapse there.

Some of the the strikes, carried out by the military’s Joint Special Operations Command (JSOC), have been focused in the southern part of the country, where insurgent forces have for the first time conquered and held territory as the Yemeni government continues to struggle against escalating opposition to President Ali Abdullah Saleh’s 33-year rule.

Unlike in Pakistan, where the CIA has presidential authorization to launch drone strikes at will, each U.S. attack in Yemen — and those being conducted in nearby Somalia, most recently on Thursday near the southern port city of Kismayo — requires White House approval, senior administration officials said.

The officials, who were not authorized to discuss the matter on the record, said intended targets must be drawn from an approved list of key members of al-Qaeda in the Arabian Peninsula deemed by U.S. intelligence officials to be involved in planning attacks against the West. White House counterterrorism adviser John O. Brennan last week put their number at “a couple of dozen, maybe.”

Although several unconfirmed strikes each week have been reported by local media in Yemen and Somalia, the administration has made no public acknowledgment of the escalated campaign, and officials who discussed the increase declined to provide numbers.

The heightened air activity coincides with the administration’s determination this year that AQAP, as the Yemen-based group is known, poses a more significant threat to the United States than the core al-Qaeda group based in Pakistan. The administration has also concluded that AQAP has recruited at least a portion of the main insurgent group in Somalia, al-Shabab, to its anti-Western cause.

From its initial months in office, the Obama administration has debated whether to extend the air attacks that have proved so effective in Pakistan to the Arabian Peninsula and the Horn of Africa. Military and intelligence officials have long argued in favor of attacks against al-Shabab camps in Somalia, which have been under overhead surveillance for years. Other officials have questioned the legal and moral justification for intervening in what, until recently, has been a largely domestic conflict.

The administration has said its legal authority to conduct such strikes, whether with fixed-wing planes, cruise missiles or drones, derives from the 2001 congressional resolution authorizing attacks against al-Qaeda and protection of the U.S. homeland, as well as the international law of self-defense.

“The United States does not view our authority to use military force against al-Qaeda as being restricted solely to ‘hot’ battlefields like Afghanistan,” Brennan said in remarks prepared for delivery Friday night at Harvard Law School. “We reserve the right to take unilateral action if or when other governments are unwilling or unable to take the necessary actions themselves.”

“That does not mean we can use military force whenever we want, wherever we want,” Brennan said. “International legal principles, including respect for a state’s sovereignty and the laws of war, impose important constraints on our ability to act unilaterally — and on the way in which we can use force — in foreign territories.”

In Somalia, the administration backs a tenuous government whose control does not extend beyond the capital, Mogadishu.

In Yemen, Saleh has been a close counterterrorism ally, and Brennan said last week that Yemen’s political turmoil, which began in March as part of the upheaval known as the Arab Spring, has not affected that cooperation. U.S. officials have emphasized that violence between loyalist troops and those backing breakaway army officers and tribal leaders has not involved U.S.-trained Yemeni special operations forces. This week, government forces reportedly made gains fighting against entrenched insurgent fighters in the southern port town of Zinjibar.

In the Yemeni capital Sanaa, thousands of anti-government protesters have been camping out in what is known as Change Square for several months, demanding an end to Saleh’s rule. The camp has remained quiet for weeks, but Reuters, citing doctors, reported Saturday that soldiers opened fire near the camp overnight and wounded eight protesters. The troops shot in the air to stop demonstrators from trying to expand the area of protest.

As the political conflict drags on, concern has increased over insurgent expansion and future cooperation with whatever government emerges in Yemen.

For months, the administration has called on Saleh to sign an agreement put forward this summer by Persian Gulf states to transfer power to an interim government and hold early elections. His intransigence seems to have increased since June, when Saleh departed for medical treatment in Saudi Arabia after being severely injured in an attack on his presidential palace. He has repeatedly insisted he intends to return to Yemen and retake control of his government, currently being run by Vice President Abed Rabbo Mansour Hadi.

Last week, the ruling General People’s Congress sent a delegation to Riyadh and secured Saleh’s agreement to allow Hadi to negotiate with the opposition and implement a political transition. While the opposition called the deal a trick, the Obama administration has tried to push Hadi and the government to take the initiative and negotiate a deal with opponents.

In a statement released late Thursday, the State Department called on the Yemeni government to sign and implement the agreement “within one week.”

Until May, the first and only known drone strike in Yemen was launched by the CIA in 2002. As part of its stepped-up military cooperation with Yemen, the Obama administration has used manned aircraft to strike at targets indicated by U.S. and Yemeni military intelligence forces on the ground. In May, JSOC first used a drone to kill two AQAP operatives as part of its new escalation in Yemen.

This summer, the CIA was also tasked with expanding its Yemen operations, and the agency is building its own drone base in the region. It is not clear whether the unilateral strike authority the CIA has in Pakistan will be extended to Yemen.

Administration officials have described the expanded drone campaign as utilizing a “mix of assets,” and a senior military official said he knew of no plans or discussions “to change the nature of operations.”

“The new base doesn’t connote that [the CIA] will be in the lead,” the official said. “It offers better teamwork and collaboration between the agencies.”

Staff writer Greg Jaffe contributed to this report.