The Obama administration has laid out a new national counterterrorism strategy, saying its focus is the destruction of al-Qaida and its affiliates in Yemen, Pakistan, Somalia and elsewhere.

The administration's top counterterrorism adviser, John Brennan, discussed the plan in a speech in Washington Wednesday.

The former CIA officer said the United States and partners including Pakistan and Yemen have strangled al-Qaida's finances and decimated its leadership ranks.

But he said the serious threat from al-Qaida is not over. He said the terrorist group may try to mount revenge attacks for the death of its leader, Osama bin-Laden, who was killed in a raid by U.S. special forces in Pakistan last month.

Brennan also said the new strategy is the first one that designates the U.S. homeland as a key area of emphasis in counterterrorism efforts. He said it focuses on the ability of al-Qaida and its affiliates to inspire people in the U.S. to carry out attacks in the country.

In one of the best-known cases, a U.S. Army psychiatrist, Major Nidal Hasan, is charged with killing 13 people at Fort Hood in Texas in 2009. Hasan was allegedly inspired by a radical U.S.-born cleric in Yemen believed to have close ties with al-Qaida.

In his speech Wednesday, Brennan said the so-called Arab Spring uprisings in the Middle East have undermined al-Qaida's ideology and its ability to attract new recruits. But he said terror organizations and nations that support them will likely seek to capitalize on the instability that change can sometimes bring.

He said the U.S. counterterrorism strategy is the first one to reflect the major political changes sweeping through the Middle East and North Africa.

Brennan also said Iran's nuclear activities remain a concern.