Al-Shabaab, which means "youth" in Arabic. Also known as Mujahideen Youth Movement, Harakat Shabab al-Mujahideen, Hizbul Shabaab, Al-Shabaab al-Islamiya, Youth Wing, Al-Shabaab al-Islaam, al-Shabaab al-Jihaad and the Unity of Islamic Youth.

Somalia. Recruiting efforts on behalf of the group have been reported among Somali expatriates in the United States.

Al-Shabaab seeks to drive foreign forces out of Somalia and to create an Islamic state in place of the Ethiopian-supported government.

Before the Ethiopian invasion, estimates of Al-Shabaab strength ranged from several thousand to 6,000. The group's current strength is unknown.

Eritrea has allegedly provided substantial support for Al-Shabaab, including providing guerrilla training for group members in Eritrea. Senior members of Al-Shabaab are believed to retain links to Al-Qaida after training and fighting in Afghanistan against the Soviets in the 1980s. The group's leaders have called on foreign Islamist fighters to join them in the fight against what they call the infidels in Somalia.

Al-Shabaab has engaged in terrorist activities in Mogadishu, including assassinations attempts against Somali government officials and attacks on Ethiopian and other foreign forces in Somalia. Though most of the terrorist activity has occurred in Mogadishu, the group also began a campaign to capture and hold territory in southern Somalia in early 2008.

Al-Shabaab emerged in mid-2006 as a splinter group from the Islamic Courts Union movement in Somalia. Though the reasons for the split are not clear, Al-Shabaab is generally seen as more extreme and often described as the hard-line wing of the ICU. As the name suggests, many Al-Shabaab members are young men in their 20s.

The group is believed to be led by Aden Hashi Ayro, a guerrilla in his 30s who reportedly spent most of the 1990s in terrorist training camps in Afghanistan.

Al-Shabaab played a major role in helping the Islamic Courts Union oust the warlord alliance from power in Somalia in 2006. However, the group was scattered by advancing Ethiopian forces in December 2006 and January 2007. Ayro and his inner circle fled Mogadishu for southern Somalia as the Ethiopians approached, likely finding refuge near the border with Kenya.

Al-Shabaab quickly reformed and began mounting a guerrilla campaign from its southern strongholds against Ethiopian and Somali government forces.

The group remained a strong, if not dominant, presence in southern Somalia in mid-2009. The interim national government, protected by more than 4,000 African Union troops, has maintained its presence in the capital of Mogadishu. Al-Shabaab, however, has continued to carry out attacks in the capital and to seize villages elsewhere in the country. Al-Shabaabhas shown an ability to recruit members from outside of Somalia, including a handful from the U.S.

November: The U.S. announced support for a U.N. resolution calling for African peacekeepers in Somalia.

Dec. 24: Ethiopia began a major military offensive against Al-Shabaab and the Islamic Courts Union in Somalia.

Dec. 27: Al-Shabaab and ICU leaders fled Mogadishu ahead of advancing Ethiopian troops.

Jan. 7: With approval from the Somali government, A U.S. Air Force AC-130 Spectre gunship launched air strikes against suspected Al-Qaida members in southern Somalia. The senior terrorist leaders who were targeted apparently survived the attack.

Jan. 22: The U.S. launched a second AC-130 air raid on terrorist targets in southern Somalia.

March 6: The first of 1,600 Ugandan peacekeepers arrived in Mogadishu to participate in the African Union peacekeeping mission.

March 22: The Somali government said Al-Qaida had named Aden Hashi Ayro as the leader of Al-Shabaab.

July: Al-Shabaab launched rockets and mortars at a national reconciliation conference in Mogadishu.

Oct. 7: Robow Abu-Mansor was named commander of Al-Shabaab.

Dec. 22: Al-Shabaab announced the appointment of Abdirahman Abu-Zubeyr as the group's new commander, taking over from Robow Abu-Mansor.

Jan. 18: The African Union warned that Al-Shabaab was spreading to previously peaceful areas, and was recruiting new members and planning attacks in the Middle and Lower Juba regions. "Their strategy seems to be to further weaken the [Transitional Federal Government] by destabilizing as many areas as possible, fully aware that the government does not, at the moment, have the capacity to deploy significant numbers of troops in all the regions," said a report by A.U. Commission Chairman Alpha Konare.

Feb. 5: Al-Shabaab detonated multiple bombs in the Puntland city of Bossaso, killing at least 20 people and injuring 70. The attack was Al-Shabaab's first in Puntland, a largely autonomous region in northeastern Somalia.

Feb. 29: The U.S. State Dept. designated Al-Shabaab as a foreign terrorist organization.

March 4: The U.S. Navy launched two Tomahawk cruise missiles that struck houses in the Somali village of Dobley near the border with Kenya. Islamists had retaken control of the village the previous week. The target was said to be Saleh Ali Saleh Nabhan, Al-Qaida's chief in East Africa, wanted for multiple terrorist attacks in Kenya.

April 24: An Al-Shabaab spokesman said the group would not hold talks with the Somali government or support peace initiatives made by Prime Minister Nur Hasan Husayn.

May 1: Aden Hashi Ayro, a key leader of Al-Shabaab in Somalia, was amongst the militants killed by a U.S. missile strike on a facility in the Somali town of Dhusamareb. The U.S. said it had standing permission from Somalia's government to conduct such strikes.

Sept. 28: Al-Shabaab released a video message pledging its allegiance to Osama bin Laden.

Sept. 28: Al-Shabaab shelled the Mogadishu airport after a commercial aircraft successfully landed there. The group had declared that no commercial flights were allowed. No fatalities or injuries were reported.

Oct. 6: The group shelled the presidential palace in Somalia. One mortar hit a nearby marketplace, killing 17 people.

Oct. 29: Al-Shabaab conducted a suicide bombing at the United Nations compound, the Ethiopian consulate and the presidential palace in Hargesis, resulting in 24 fatalities. An American citizen from Minnesota carried out the suicide attack, said the U.S. government.

February: Al-Shabaab killed 11 Burundian soldiers in an attack on African Union peacekeepers. The A.U. said the compound housing the soldiers had been targeted by mortars. The militants claimed the explosions came from suicide bombers.

March 25: Al-Shabaab militants broke up a protest by 1,000 demonstrators in Baidoa, who opposed the group's ban on the use of khat, a mild narcotic used by men in the town. Militants fired their weapons in the air to break up the protest.

April: Al-Shabaab launched a mortar attack near an airplane carrying a U.S. congressman as the aircraft took off from a Somalia airport. Rep. Donald Payne (D.-N.J.), chairman of the House subcommittee on Africa, was unharmed.

July 6: The government of Somalia rejected an ultimatum issued by Al-Shabaab that called for government forces to surrender their weapons within five days. Al-Shabaab said it intended to put government leaders on trial for actions leading to the death of civilians and for encouraging the re-occupation of Somalia by foreign armies.

July 10: Members of Al-Shabaab denied that the group had beheaded seven people. News reports, citing accounts from relatives of the slain captives, said the victims were executed without trials. The militant group admitted only that it had seized the seven people.

July 18: An Al-Shabaab official said sharia law would be used to conduct a trial of two French security advisers kidnapped by the group. The advisers were part of an official mission to train the forces of the interim government.