It doesn't take a barbarian to kill hundreds, even thousands of people. It just takes one illegal alien with a killer strain of anti-biotic resistant swine flu. One guy, feeling perfectly healthy but carrying the disease in an incubating state, who crosses the border, and gets sick.
Read "The Stand" by Stephen King. Just one Captain Tripps can wipe out all of North America. Just one Typhoid Mary with a particularly killer strain of a disease can wipe out whole cities. It has happened before... not on the scale of The Stand, to be sure, but it has happened.
The Bubonic Plague wiped out 50-60% of Europe's population between 540 and 750 CE.
The Black Plague killed over 25 million in a 5 year period in the mid 14th century.
In 50 years, between 1518 and 1568, the Mexican population dropped from 20 million to 3 million due to Typhus and Smallpox brough over by Europeans.
In 1918, the Spanish Flu killed 25-50 million people or about 2% of the world's population at that time.
Today, 250,000 to 500,000 people die each year of the COMMON flu. Swine flue is more virulent.
One accident is all it takes to turn this from a pandemic to an EPIDEMIC.
Why should we not protect ourselves by controlling the borders?
Elliot