Violent extremist networks based in the Horn of Africa may be evolving and groups such as the Islamic Shebab militants will likely pose a regional threat for some time, top US officials said Tuesday.

Last month's attack on an upscale mall in Kenya, which has been claimed by the Somali-based Shebab, shows the need for the United States to keep up its support to the fledgling authorities in Somalia, Pentagon and State Department officials told US lawmakers.

The four-day Nairobi mall siege, which left at least 67 people dead and another 39 still listed as missing, was "a chilling example of the challenges for Somalia and the region," Assistant Secretary for African Affairs Linda Thomas-Greenfield said.

"This attack suggests that violent extremism in the Horn of Africa may be evolving," she told the Senate Foreign Relations committee.

Helping Somalia, as it emerges from two decades of civil war, build a peaceful, stable nation will "in turn prevent terrorists from using Somali territory as a safe haven," she insisted.
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An Islamist fighter loyal to Somalia's Al-Qaida inspired …
An Islamist fighter loyal to Somalia's Al-Qaida inspired Shebab group holds his arms during military …

Deputy Assistant Secretary of Defense Amanda Dory warned that although the Shebab had been weakened by fighting with Somali, Ethiopian and the African Union AMISOM forces it was "still dangerous and capable of conducting sophisticated unconventional attacks."

"For the foreseeable future, we must maintain focus on Somalia to sustain security progress made to date, as Shebab is likely to remain the primary threat to Somalia and East Africa stability for some time to come," Dory said.

But the US administration officials came under fire from veteran Senator John McCain for what he called "a failed" mission at the weekend to capture a one of Shebab's commanders from his house in the port of Barawe.

Abdulkadir Mohamed Abdulkadir, a Kenyan of Somali origin who fights for the Shebab under the alias "Ikrima, was the target of the strike, but it remains unclear whether he was killed in the weekend firefight.

Pentagon officials have acknowledged he was not captured after US Navy SEALs were reportedly forced to abandon their raid when they came under fierce fire.

Neither Dory nor Thomas-Greenfield would go into details about the operation in public, saying they could only address it in a classified session.

"With sustained assistance from the United States and other international partners, Somalia’s national security apparatus will be better positioned to fend off the al-Shebab insurgency and gradually transform the fragile state into a success story," Dory added.