The anniversary of Osama bin Laden’s death last week focused attention briefly on the continued threat posed by al Qaeda Central. But what about al Qaeda's franchises elsewhere, like al Shabaab in Somalia? The viability of the threat these groups pose to the U.S. deserves more careful consideration than it has received.

The structure and leadership of al Shabaab are of paramount importance to understanding how this radical Islamist group operates in Somalia.

Denial of access by al Shabaab militants, and in some cases by other armed militias, is the single greatest obstacle to the provision of humanitarian assistance in Somalia.

As the international community and the US discovered in the early 1990s, getting humanitarian aid to needy Somalis is not an apolitical undertaking. It may not even be possible without being drawn into conflict in the Horn of Africa once again.

Al Shabaab's rhetoric has evolved over time and developed an increasingly global militant Islamist undertone as the group has gained strength in Somalia.

Recruiting Westerners has become a top priority for Somalia's al Qaeda-linked terrorist group al Shabaab, worsening an already severe threat posed by the global Islamist movement.

The United Nations has recently ratcheted up its criticism of the United States' decision to withhold humanitarian aid to parts of Somalia controlled by the Islamist terror group al Shabaab.

One month after al Qaeda released its first English-language magazine in the Arabian Peninsula, al Shabaab released its first professional-quality English-language "news" broadcast to jihadi web forums last week seeking to attract Westerners to its ranks.