In 2006, David Kilcullen stated that there has been more written about insurgency in the last four years then the last four decades, when the terminology was created. Terrorist organizations, in recent history, have been conducting operations similar to insurgents, such as living among the population in highly urbanized areas, where they conduct both recruiting and operations. It is important to note that this increased interest in terrorism is not based upon a single event, but in an increasing trend in terrorist attacks. From the years 1968-1997, the global average number of attacks ranged between 243 and 305 events annually. However, since 1997, that number has increased more than 6 times resulting in between 1589 to 1895 events per year. Between these time periods, the lethality of terrorist attacks have also increased. The United States government states that it has "no greater responsibility then ensuring the safety and security of the American people." Today, the global terrorism threat presents the greatest viable threat to the American people and therefore, is one of the main focuses of the United States government, as well as the rest of the world. Despite the importance of the issue, little is known about modern terrorism. Partially, this is due to the nature of today's insurgents, who differ significantly in terms of "policy, strategy, operational art, and tactical technique" from past insurgents. Consequently, this puts the United States and the world as a whole in a position where we know little about this global threat. Furthermore, this lack of understanding of this adversary has caused the U.S. to take a reactionary stance to countering terrorism, instead of a preventative stance.