The US ambassador denied the existence of any US military bases in Tunisia, but said al Qaeda-linked groups such as Ansar al Sharia continue to threaten Tunisia. At a gathering yesterday in Sidi Bouzid marking the third anniversary of the start of the Tunisian revolution, the outlawed group Ansar al Sharia and an allied organization, Hizb ut Tahrir, carried banners calling for the imposition of sharia law, the return of the Islamic caliphate, and the release of terrorist detainees, and distributed leaflets demanding that Ansar al Sharia no longer be deemed a terrorist group and that the Terrorism Act be rescinded. The Interior Ministry had warned Ansar al Sharia that it faced prosecution if it appeared at the Sidi Bouzid gathering. Authorities are becoming concerned that hundreds and perhaps thousands of Tunisian youth have been recruited for jihad in Syria and elsewhere.