If any of the hijackers could not reach their intended targets, they were to crash the plane. Bin Laden recommended four individuals for the plot, including Nawaf al-Hazmi, Khalid al-Mihdhar, Walid Muhammad Salih Bin 'Attash (Khallad), and Abu Bara al-Taizi. Al-Hazmi and al-Mihdhar were both Saudi citizens, which made it straightforward for them to obtain U.S. visas, unlike Khallad and al-Taizi who both were Yemeni citizens, and as such unable to get visas to the U.S. easily. The two Yemenis were assigned for the Asia component of the plot. When Mohamed Atta and other members of the Hamburg cell arrived in Afghanistan, bin Laden was involved in selecting them for the plot and assigned Atta to be its leader. At the time, Khalid Sheikh Mohammed led al-Qaeda's 'military committee'. He provided operational support, such as selecting targets, and helped to arrange travel for the hijackers. Khalid Sheikh Mohammed explained to Fouda, "We had a large surplus of brothers willing to die as martyrs. As we studied various targets, nuclear facilities arose as a key option"...but the nuclear targets were dropped for concerns the plan would "get out of hand." Hamburg cell Mohammed Atta, Ramzi bin al-Shibh, Marwan al-Shehhi and Ziad Jarrah came into the picture in 1999, when they arrived in Kandahar from Germany. The Hamburg cell was formed in 1998 shortly after Atta received Al-Qaeda leadership approval for his plot. Mohamed Atta, Marwan al-Shehhi, Ziad Jarrah, Ramzi bin al-Shibh, Said Bahaji, Zakariyah Essabar, and fifteen others were all members. Mohammed Atta was religious, but not fanatically so, when he came to Germany in Fall 1992 to study urban planning at the Technical University of Hamburg. While in Germany, he was drawn to Al Quds Mosque in Hamburg, which then adhered to a "harsh, uncompromisingly fundamentalist, resoundingly militant" version of Sunni Islam. A friend of Atta's recalled meeting him at the Al-Quds mosque in 1993, though it is unknown when he began going there. Atta had lived as a strict Muslim, but after making a pilgrimage to Mecca in 1995, he returned to Germany more fanatical than before. In late 1997, Mohamed Atta told his roommate that he was going to Mecca, but likely he went to Afghanistan instead. According to Al Jazeera journalist Yosri Fouda, Atta went to the mosque around this time "not to pray but to sign his death will." He was known to have attended Al-Qaeda