A recent analysis of data accumulated by the National Consortium for the Study of Terrorism and Responses to Terrorism (START) at the University of Maryland reveals a disturbing depth to the level of extremism and violence perpetrated within the United States over the past decade.

In sum, START’s Global Terrorism Database, an open-source database comprising “information on over 87,000 domestic and international terrorist events around the world since 1970,” identified over 200 acts of terrorism having occurred in the United States since 2000. Of those acts, 17 resulted in fatalities.

While the motivating factors underlying these acts varied considerably, ranging from Islamist-inspired “lone wolves” to actors within the Animal Liberation Front and Earth Liberation Front, the implications of such violence on America’s strategic effort to protect the homeland is profound.

Looking at the numbers more closely, START noted that since 9/11, 32 people have lost their lives due to terrorist acts committed in the United States. The single most lethal incident was the 2009 Fort Hood shooting by Army Major Nidal Malik Hasan, in which 13 people were killed.

Recently, much of the focus within America’s broader national security apparatus has rightly been given to the emergent threat of homegrown Islamist radicalization. A look at START’s data substantiates that focus.

START identified 211 individuals who were radicalized in North America “to the point of supporting violence” between 1989 and 2011. Of the individuals identified, each was either indicted for violent crimes, was killed while supporting Islamist activities, or had publicly aligned themselves with known Islamist organizations.

While much attention has been given to more recent examples of domestic radicalization, such as the 2010 arrest of Faisal Shahzad or the 2009 arrest of Najibullah Zazi, the START study on Islamist radicalization in North America shows it to be a protracted phenomenon having long affected our nation’s homeland security.

The START data underscores the need for the United States to maintain vigilance in what amounts to a multifaceted effort to inhibit and contain the ill effects of Islamist radicalization and any outgrowth of violence that may result.

Our collective national security infrastructure should emphasize both counter-radicalization efforts and robust and integrated counter-terrorism programs emphasizing the active participation and cooperation among federal, state, and local law enforcement. The START analysis is a stark reminder that the threat of violent extremism is neither new nor diminishing.