It certainly is if:
A. They're throwing rocks at border guards.. rocks are perfectly lethal projectiles, and have been for thousands of years.
B. They were told repeatedly, BY ACTUAL AGENTS OF THE U.S. GOVERNMENT, to stay back, not try to cross, and that attempting to cross is an illegal act.
C. We have no idea WHY they're crossing illegally since they haven't been vetted; for all we know they're breaking in to commit terrorism... it is pure presupposition to assume that people breaking our laws and ignoring government agents to break into our country illegally are actually just a nice bunch of guys with good intentions.
D. The act of crossing a border illegally is, in itself, a criminal act against a sovereign nation... even without the violence it can be considered an attack on our "sovereignty", on our "laws", and on our "border."
* And one last time: go throw a big rock at a policeman, and see if you don't get arrested for "attacking him."
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