Domestic Terrorism

I haven't heard anyone calling the violence and threats of violence against Democratic members of Congresss domestic terrorism, but they are. They are aimed at intimidating these elected officials, at making them think twice before taking principled but unpopular positions. And then there was the sign at a recent rally:

I am in favor of free speech, but when a sign suggests that a handgun is a way to achieve a political end aren't we dealing with a threat of violence, with domestic terrorism?