If they had a fence to cross

Then they'd have known that they were on the wrong side of it...

"Those individuals were part of a counter-narcotics operation, which had taken place a few minutes prior on the Mexican side of the border. The two members of the Mexican army did not see any sign notifying them that they were crossing the border."


Wrong side of the border...ok, I can accept that they, without any markings, might have made a mistake. 

But holding Customs and Border Patrol agents at gunpoint? 

Yeah, one wonders....

Were they escorting someone?

And is anyone working for Barry doing anything to keep this from happening again.