Islamist fighters in Somalia threatened Friday to avenge the death of a reputed Al Qaeda commander killed in a U.S. airstrike and warned Americans to stay out of the Horn of Africa nation.

U.S. missiles destroyed the house of Aden Hashi Ayro in the central Somali town of Dusamareeb on Thursday in the first major success in a string of such U.S. military attacks over the past year.

Ayro's assassination comes amid escalating fighting and a spiraling humanitarian crisis in the country that has killed thousands of civilians and driven hundreds of thousands from their homes in the past year.

"This will not deter us from prosecuting our holy war against Allah's enemy," Sheik Muqtar Robow, a spokesman for the al-Shabab militia that Ayro led, told The Associated Press in a telephone interview. "If Ayro is dead those he trained are still in place and ready to avenge against the enemy of Allah.

"We know our enemy. It is impossible to hit missiles on our people and we let your citizens come to our country," he said, adding: "We warn them to stay out of our country."

The warning also applies to citizens of countries friendly to the United States and to neighboring Ethiopia, which has sent troops to fight Somalia's Islamist insurgency, he said.

Twenty four other people were killed in the attack, said one of the Dusamareeb elders, Ilmi Hassan Arab. Five of the bodies were in the targeted house and the rest from nearby homes, he said.

Robow said another senior al-Shabab leader, Sheik Muhidin Mohamud Omar, also was killed in the attack.

Al-Shabab is the armed wing of the Council of Islamic Courts movement, which seized control of much of southern Somalia, including the capital, Mogadishu, in 2006. Ethiopian troops allied with Somalia's shaky, U.N.-backed interim government invaded to drive the movement from power in December 2006.

Since then, al-Shabab has pursued an Iraqi-style insurgency, with roadside and suicide bombings and assassinations. In recent months, the militia has briefly taken several towns, freeing prisoners and seizing weapons from government forces. The insurgents usually withdraw after a few hours but continue to target Ethiopian and Somali forces.

The State Department considers al-Shabab a terrorist organization.

"You have left us as martyrs and we vow to avenge your deaths with God's help," Al-Shabab said on their internet site.

Analysts say Thursday's attack could torpedo U.N.-backed peace talks scheduled to start May 10, which were slated to be more inclusive than previous rounds and offered a slim hope of bringing together the disparate groups in the armed opposition, including some Islamists.

The biggest alliance supporting Somalia's Islamist insurgency says it is considering pulling out of the peace talks, said Sheik Sharif Sheik Ahmed, the exiled chairman of the Alliance for Liberation and Reconstitution of Somalia.

The alliance brings together moderates and Islamist hard-liners inside Somalia and in exile.

The United States has often accused Islamist Somalis of harboring international terrorists linked to Al Qaeda, including those blamed for the deadly 1998 bombings of the U.S. embassies in Kenya and Tanzania.

The U.S. has backed Somali warlords promising to fight the insurgents, including some accused of human rights abuses. That strategy has deepened anti-American sentiment.

There are many different and shifting alliances in the insurgency. One faction made up of warlords, politicians and businessmen is willing to take part in the peace talks. Its primary concern is the withdrawal of Ethiopian forces.

But there are more extreme elements, especially among the al-Shabab militia that opposes the talks.

In the past year, the U.S. military has attacked several suspected extremists in Somalia — most recently in March, when the U.S. Navy fired at least one missile into a southern Somali town. The attack targeted Saleh Ali Saleh Nabhan, a Kenyan suspected in the 1998 embassy attacks.

Somalia has been without an effective government for nearly 20 years.