"The threat from Al-Shebab to the US and Western interests in the Horn of Africa and to the US homeland is significant and on the rise," Panetta says in written responses to the Senate Armed Services committee.
Panetta is to attend Thursday`s hearing as the Senate considers his nomination to be the next secretary of defense to replace Robert Gates.
"Al-Shebab leaders, who have claimed affiliation with Al-Qaeda since 2007, are developing ties with Al-Qaeda in the Arabian Peninsula, and are showing an increasing desire to stage international terrorist attacks in addition to their acts of violence inside Somalia," he says in his written text, a copy of which was obtained by AFP.
Panetta was nominated on April 28 by President Barack Obama to replace Gates who retires on June 30. His nomination has to be confirmed by the Senate.
"Al-Shebab employs several hundred foreign fighters and regularly tries to recruit fighters from Somali diaspora communities in the United States and Europe," Panetta writes.
As the Islamist movement, which controls much of Somalia and a large part of the capital Mogadishu, "faces increasing international pressure, we may see the group increase its international attacks," he warns.
The Shebab carried out its first attack outside Somali territory in July 2010 when it claimed a double bombing in which 79 people died in Kampala.
Panetta warned that Somalia, which has had no effective government since dictator Siad Barre was deposed in 1991, could become a new haven for Al-Qaeda, whose leader Osama bin Laden was killed in a US commando raid on May 2.
"As Al-Qaeda undergoes leadership changes and regroups from
counterterrorism operations in Pakistan, we need to ensure that it does not relocate its center of operations to Somalia," Panetta says. (*)