But this is a thorny issue which BMW is reluctant to discuss - beyond Mr Biggs' insistence that "our business is in good shape".

BBC: NEWS | Business | Rolls-Royce plans convertible future

From Baghdad to Okinawa, this is a thorny issue, and now is not a good time in Kabul to negotiate an agreement guaranteeing American troops immunity from local prosecution even after 2014.

ECONOMIST: Afghanistan