From Time magazine today:

Joint U.S.-Afghan operations are plagued by mistrust, with the living quarters of allied and Afghan troops separated by walls, razor wire, guarded gates and machine-gun nests. "Currently, coalition forces eat, sleep and play in separate spaces from the people they are trying to train," U.S. Marine Captain Jason Moore noted in a report earlier this year for the Corps' Command and Staff College at Quantico, Va.

Why?

In part, that's because Taliban sympathizers in the Afghan military have shot and killed U.S. troops.

That's why.

But Captain Moore is  troubled by the message walls, razor wire and machine-gun nests are sending:

"Intentional or not, it conveys a sense of distrust, hostility and disrespect to their hosts."

I give up.