There is actually a very brutal fact in this ... simulations show that to enforce a true quarintine, troops would have to be willing to kill Americans attempting to run roadblocks.  In all simulations, even when the soldiers and National Guardsmen were shootin blanks ... they refused to shoot those blanks at the civilians.

This is harsh math, but in the simulations "not killing" a few hundred at roadblocks leads to (in worst cases) millions dying in other cities.

Not nice, but I believe that really is the way it goes.

* - I suppose a historian would say it goes by thousands of years.

When thinking about big picture, when the question is about saving human species, you have to give away such humanism-christianity which tells not to kill a human. When there is 5 billion large carnivorous too many on this tiny planet with huge consumption rate, this species nor, in the worst case, even the whole biosphere has no future if human population is so huge. If human species if important to you, start killing people. If not, why not kill yourself right away, how can one human life be important, while the whole species future is not. Every act of terror which decreases consumption and/or production will give this biosphere few more minutes, days or perhaps years.