THE war the West is waging in Afghanistan is awash with
“metrics” meant to gauge progress. Now an ominous set of figures
is drawing scrutiny. This year troops from the NATO-led
coalition have frequently been attacked by their local allies in
the Afghan security forces. In 34 “green-on-blue” attacks this
year, 45 soldiers have been killed and 69 wounded. In the most
recent incident, on August 29th, an Afghan soldier shot dead
three Australian soldiers at a base in the south-central
province of Uruzgan.  One in seven of all NATO deaths this year
has thus been at the hands of the very Afghan troops the
coalition is trying to help and train. The habit appears to be
growing. This year’s death toll has already surpassed 2011’s
total of 35. President Barack Obama admits to deep concern in
Washington over this trend.  Yet what is causing the attacks,
and how they can be stopped, remains unclear. Very few of the
attackers have been taken alive, since most were shot dead in
self-defence or fled after their attacks. Wit