As President Barack Obama struggles to reassure Americans that his administration has a handle on terrorism, specialists in the burgeoning field of countering violent extremism (CVE) say the US government should devote more resources to domestic programs that can prevent susceptible youth from succumbing to the approaches of terrorist groups.

In the aftermath of the San Bernardino shootings, political candidates such as Donald Trump have focused on the threat of terrorists entering the United States from abroad. But so far, those responsible for the most mayhem in the United States have been US citizens who “self-radicalize” through contacts on the Internet or with other recruits.

According to a new study by the George Washington University Program on Extremism, of the 71 individuals arrested in the United States since 2014 on charges of links to the group that calls itself the Islamic State (IS), 58 were American citizens, six were permanent residents and nearly half were converts to Islam.

Meanwhile, the number of Americans lured into traveling to Iraq and Syria remains relatively small, about 250, compared with thousands of Europeans and others who have sought to join jihadi groups.