"One man's terrorist is another man's freedom fighter." In the dark days following 9/11, this aphorism fell out of favor, but it was once espoused by a US senator in support of violence that cost two thousand people their lives in a country the size of Maryland.

Deployed to a US Navy base in Northern Ireland, Richard Chase watches as arms, ammunition, and explosives purchased with money from Irish Americans flow into Northern Ireland for use against the United States' British allies. IEDs, car bombs, kidnappings, and shootings are daily events, as is collateral damage to US military...