Return to sender?

The (Edinburg) Scotsman had the best reporting on this quasi-non-event from Monterrey.  But, then, the Scots are known for both eschewing speculation and being as parsimonious with their words as they are with everything else:

TWO gunmen yesterday shot at a US consulate in Monterrey, northern Mexico. They also threw a grenade at the building but it did not explode and no-one was injured, officials said.

The consulate, which processes immigrant visas for Mexicans and provides services to US citizens in Mexico, was closed for the Columbus Day holiday.

Having no idea why, or who might — or might not — be involved, the other press reports go into the recent history of hand grenade tossing in Mexico, and narcotics dealing and even mention Arab terrorists. Were I to indulge my taste in speculation, I might just note that alleged “terrorist” acts at night, on holiday weekends when no one will be injured (and the hand grenade was tossed without pulling the pin) has been used before in Mexico to create a rationale for state action against imaginary “terrorist groups.”

Or, more likely, the grenade tossers wanted to return their defective purchase to the place of origin, but couldn’t get back in the U.s. and the consulate was the next best thing.