May LP Members Kill Government Employees?

The Libertarian Party, through it oath or pledge, takes the position that the initiation of force is bad, but the use of force to retaliate or defend is good. But what does this mean? The LP has yet to explain. What if an LP member enters a federal building and kills several employees of the Internal Revenue Service? If the oath or pledge means that the LP rejects political violence, then the act can be condemned and the the perpetrator expelled from the party. But if the oath or pledge means that violence is permissible to retaliate or defend against another who has initiated force, then the LP would have to defend the actions of the perpetrator. After all, the IRS initiates force when it enforces the collection of the income tax and other taxes. So the perpetrator is engaging in retaliatory or defensive action whey he kills the IRS employees. Please note: the two aforementioned interpretations of the oath are not complementary; they are diametrically opposed to one another. Yet LP members claim that political action and personal action can be judged according to the same principle.