No, it's saying that if all you're going to do to secure your house is to lock the front door, and you're going to leave the windows and back door propped open, you haven't achieved your stated goal. You haven't even come close.
The fact is, our border with Mexico is the number one problem confronting this nation with regard to illegal border crossings. Further, those border crossings are not limited to Mexican citizens. Middle-eastern, Chinese, south-American, European and other groups have been identified coming across our southern border.
And many of those Middle Easterners will simply come across the wide-open Canadian border, or come in "over the beach."
At least one individual has been documented coming across our southern border, traveling to Chicago, and doing his best to become connected to other like minded individuals in order to carry out a terrorist act on U.S. soil.
If it's who I'm thinking of, he actually came into the United States at O'Hare International Airport on a flight from Switzerland.
It's not, but then facts have never been your strong suit on this issue.
It makes no sense to you to close the border on which over 50% of illegal immigration occurs, simply by walking across on dry land, because "that would leave the back door open."
Okay ace, what is the good of declaring a war on terrorism then leaving every door open?