In May 2003, Islamist suicide bombers simultaneously struck a series of sites in Casablanca, killing 45 and injuring more than 100 others. The Moroccan government responded with a crackdown against Islamist extremists, ultimately arresting several thousand, prosecuting 1,200, and sentencing about 900. Additional arrests followed in June 2004. That same month, the United States designated Morocco a major non-North Atlantic Treaty Organization ally, stating that it was in recognition of its efforts to thwart international terrorism. On 1 January 2006, a comprehensive bilateral free trade agreement between the United States and Morocco took effect. The agreement had been signed in 2004 along with a similar agreement with the European Union, Morocco's main trade partner.