John Brennan, Assistant to US President Barack Obama for Homeland Security and Counterterrorism, speaks about US policy towards Yemen at the Council on Foreign Relations in Washington, DC, August 8, 2012. (Saul Loeb/AFP/Getty Images)

President Obama’s chief counterterrorism adviser on Wednesday defended the administration’s strategy to stem the growth of al-Qaeda’s affiliate in Yemen, saying its use of targeted killing is part of a wider approach that includes humanitarian, development and military assistance.

The remarks by John O. Brennan at the Council on Foreign Relations were prompted in part by criticism from foreign policy experts who have argued that U.S. airstrikes in Yemen do not address the underlying causes of extremism there.

“Targeted strikes,” a group of 27 prominent U.S. foreign policy experts said in a letter to Obama in June, are “not a sustainable solution” to terrorism.

Drone strikes and other airstrikes in Yemen have dramatically increased this year. Obama has authorized at least 41 strikes, the majority of them this year, according to figures compiled by the Washington-based New America Foundation. At least 10 alleged militants were killed in two separate strikes Tuesday, Yemen’s official news agency said.

On Wednesday, however, Brennan said that the focus on targeted killing ignores the administration’s “comprehensive approach.”

“This year alone, U.S. assistance to Yemen is more than $337 million. Over half this money, $178 million, is for political transition, humanitarian assistance and development,” he said.

Yemen is one of the world’s poorest and least-developed countries.

Brennan praised Yemeni President Abed Rabbo Mansour Hadi’s efforts since taking over in February, and he warned former president Ali Abdullah Saleh and his supporters to abide by an internationally negotiated agreement under which Saleh stepped down after 33 years in power.

The administration has tried to separate its targeted attacks on leaders of al-Qaeda in the Arabian Peninsula who have international terrorism ambitions from the aid it gives Yemen’s security forces to combat domestic insurgency by AQAP and other groups.

“We’re not involved in working with the Yemeni government in terms of direct action or lethal action as part of that insurgency,” Brennan said.

With U.S. intelligence help and other indirect assistance, Yemeni forces this summer routed AQAP forces that had overtaken the southern towns of Jaar, Lawdar and Zinjibar. A senior Yemeni official said in an interview that development assistance is urgently required in those areas to prove to the local populations that the government is capable of meeting their needs.

The militants “did smart things, like digging wells and hooking up electricity and telephones. People now have higher expectations,” said the official, who spoke on the condition of anonymity to press for early delivery of promised U.S. aid.

Among other issues, Brennan said Obama will use executive powers to implement some of the measures contained in cybersecurity legislation that died after a filibuster by Senate Republicans last week.

“If Congress is not going to act on something like this, then the president wants to make sure that we’re doing everything possible,” Brennan said. “Believe me, the critical infrastructure of this country is under threat.” He did not specify the actions the White House might take.

Brennan also said that recent leaks of national security information had been “devastating.” He would not discuss specific examples.

“I don’t want to validate any of the things that are out there,” he said. “But it’s unconscionable what has gone out.”

Congress and the Justice Department are investigating recent media reports detailing U.S. activities in Yemen, Iran and elsewhere.