According to news reports , the perpetrators said that they were motivated by a desire to retaliate for crimes by U.S. soldiers in Afghanistan and that they wanted to kill military personnel to prevent them from going to Islamic lands to kill Muslims . John Lewis : It 's clear that the central motivation for terrorist activity is ideological . He says for those who are radical , boiling anger at American foreign policy is the driving force .
John Lewis : It 's clear that the central motivation for terrorist activity is ideological . He says for those who are radical , boiling anger at American foreign policy is the driving force .