And the United States doesn't either. We do not have open borders. It's not easy to legally immigrate to the U.S. or to get a visa to work here.
Since you consider yourself some type of authority on keeping terrorists from illegally entering the country you should be able to link us to some scholarly works or proposals on how that could be accomplished.
Take a look at my profile page for an example of how one presents facts concerning securing the border as opposed to simply repeating the Buchanan/Tancredo propaganda myths.
The Secretary of Homeland Defense is the highest civil authority on securing the border. It is his responsibility to prevent terrorists from illegally crossing the border. He testified before two Congressional committees that the border can not be secured until certain immigration law reforms are enacted by Congress including a guest worker program that would redirect the migrant worker traffic to portals of entry.
I'm anxiously awaiting some form of authoritative facts to support your position instead of just your opinion or that of a professional fund raiser demagogue.
We do allow about one million people to legally immigrate into the United States each year, so that is very generous. To those who say we should allow more -- which is the preferred method of stopping future illegal immigration for most in the open borders crowd -- I simply ask, how many more?
Should it be 1.5 million? 2 milllion? 3 million?
If we allowed entry to anyone in the world who wanted to come here, and who met the usual caveats about not being a criminal/terrorist threat, then we could easily be overwhelmed by the sheer numbers in a very short time.