The pursuit of a political aim by means of violence and intimidation. Terrorism has existed throughout human history, but modern terrorism is sometimes said to have begun in 1968 with the hijacking of an Israeli El Al plane by Palestinians in Algeria. Terrorism has since become one of the most frequent and powerful means of waging war by many groups on many continents. The most serious incidents of terrorism on U.S. soil happened in 1995 and 2001. In 1995, 167 people were killed by a bomb placed by terrorists outside a federal building in Oklahoma City. Two anti-government Americans were convicted of the crime. On September 11, 2001, nearly 3,000 people were killed by terrorist attacks in New York City and Washington DC. These attacks were carried out by the Islamic terrorist group, Al-Qaeda. As a result of 9/11, the administration of George W. Bush launched a "war on terror" designed to defeat the threat posed by Al-Qaeda. The war on terror dominated U.S. foreign policy in the first decade of the twenty-first century, and led to the wars in Afghanistan and Iraq.