U.S. - Mexico Border Wall

Mexico Promises to Block Border Wall Plan

This seems somewhat moronic to me. Why would Mexico be complaining about a border wall when we already have walls up in some areas and a fence up in others? They are promoting illegal immigration into the U.S. How is this going to damage cross-border ties? By keeping illegal immigrants out? Why can't they cross the border legally? It's not that hard.

How, exactly, does Mexico intend on blocking this initiative? By suing us? In what court? Maybe by passing a law prohibiting the wall to go up. And since when do we follow Mexican law? Maybe they'll plead their case in the U.N. What will they do? Sanction us? Monitor the border for us? We're a sovereign nation under no requirements to have anyone other than ourselves monitor our own borders.