re: #72 Kragar
I see 3 possibilites:
a)Islamist Group, whether a Takfiri one (Al Qaida and the Like) or some group like Hezbollah.
b)Far Right Fruitcake upset by Taxes (This does remind me of Breivik)
c)A British or Irish Unionist pissed off about US Incompetence in dealing with money going to IRA during the Troubles (Boston is the most known heavily Irish City in the US).