Now that's just a wee bit over the top, don't you think? You sound like a FOBLer.
Shooting at someone on the other side of an international border is, technically speaking, an act of war against the country on the other side of the border. FReepers accuse Mexico of an act of war if someone shoots at a Border Patrol agent--and they are right to do so.
The problem here is that, because they are agents of the United States government (hence the term "border patrol agents), this act, unless it is repudiated, is casus belli--admittedly, a very small level of casus belli, but that's like being "a little pregnant." It's still pretty damn serious.