experts believe it is only a matter of time before such attacks do occur in U.S. cities.
"Bears repeating"
You couldn't be more right.
The graphic concept is misleading.
Reason being that Islamic terrorists are far more likely to infiltrate over the northern border than the southern border.
While the appearance may be superficially similar, the Islamic terrorist is far more likely to speak English than Spanish.
Fact is that most Islamists would have no indigenous support group in Mexico and would stick out like a sore thumb. But they would find entry into Canada a relatively simple matter and be able to affiliate with numerous communities once in-country.
Accordingly, for the purpose of controlling terrorism, the security of our northern border is more important than the southern border.