Al-Shabaab Islamic militants linked to al-Qaida say their suicide attack on the presidential compound in Mogadishu was aimed at killing or kidnapping Somalia's Western-backed president, Hassan Sheik Mohamud, heightening concerns the group is on the offensive again after heavy military setbacks.

Friday's coordinated attack on the presidential complex, known as Villa Somalia, "illustrated the group's ability to strike at one of the most secure locations in Mogadishu and to transition between different ways of fighting as circumstances dictate, aiding its survival," the U.S. global security consultancy Stratfor said.

"We sent well-trained mujahedin from our special forces to bring us the president dead or alive," al-Shabaab spokesman Sheik Ali Mohamud Rage said. The president was not harmed, but Rage's comments indicate he remains top of their target list.

The indications are al-Shahaab, driven out of the capital in 2011 by a strengthened African Union "peacekeeping force" offensive aided by Kenyan and Ugandan troops, is making a determined effort to regain a foothold in the war-battered capital on the Indian Ocean.

In recent weeks, al-Shabaab has been waging an escalating campaign of assassinations, bombings and attacks on military posts, "and raised the possibility of al-Shabaab re-establishing itself within the capital," Stratfor noted.

The Islamists have carried out hit-and-run raids and shellings almost nightly in recent weeks, heightening the sense that a major eruption is looming.

Omar Abdulle Ja'fan, chief of the Huriwa district, one of several Mogadishu neighborhoods being hit, told the Somali Harar24 news portal: "Al-Shabaab [members] have all but taken over this district. They're on the verge of completely taking over.

"They're pouring so many new recruits into some of the districts in Mogadishu it's unbelievable. The nights here belong to al-Shabaab."

Mohamud dismissed Friday's two-pronged assault that killed a former intelligence chief and several government officials a "media spectacular" by a "dying animal."

But the attack on the heavily fortified facility underlined that al-Shabaab has the capability to penetrate high security targets as it has been showing to deadly effect in recent weeks, as have jihadist groups fighting in Iraq and Syria.

The operation employed at least one car bomb and an assault team of gunmen dressed in Somali army uniforms and distinctive red hats of the presidential guard.

The suicide car bomb was used to blast open the heavily guarded main entrance for two carloads of attackers, who raced into the compound, dismounted and shot it out with government forces.

Some detonated bomb vests. All were killed, along with an undisclosed number of defenders.

The attackers used similar tactics in an assault on Mogadishu's courthouse last April and another on the U.N. compound in June.

Al-Shabaab used a car bomb to attack Mogadishu's airport, which is the most heavily defended facility in Somalia, Feb. 13 as a U.N. convoy was entering the airport compound where troops of the African Union Mission in Somalia are based along with several diplomatic missions, including the British Embassy.

"Unless security forces conduct a more effective counter-insurgency, the increased al-Shabaab presence in Mogadishu may cause continued attrition that could allow the group to re-establish a foothold in the capital," Stratfor cautioned.

The Islamists struck as AMISOM, now reinforced to 22,000 troops from six African countries, including Kenya and Ethiopia, is supposed to be getting ready for a new offensive aimed at driving al-Shabaab out of the large swaths of southern and central Somalia it still controls.

There doesn't appear to be any great expectation of a push anytime soon, or if one were to take place that it would make any lasting gains in a war that's dragged on for six years.

There's little evidence the transitional government is capable of moving Somalia into an era of stability.

The Horn of Africa state has been ravaged by clan wars since the collapse of Gen. Mohammed Siad Barre's military dictatorship in 1991 and Western donors are becoming impatient for some sign of progress by Mohamud's 16-month-old government.

Two weeks ago, the director of U.S. intelligence, James Clapper, voiced dismay at Mohamud's "weak leadership" and his administration's "persistent political in-fighting."

Stratfor noted the Islamists' "increased activity in Mogadishu in particular highlights the potential of a resurgence of al-Shabaab as a threat to government control within the capital."