Following the incident , in September 1937 the Nyon Conference was called by France and Great Britain to address the " underwater piracy " conducted against merchant traffic in the Mediterranean Sea . On 14 September , an agreement was signed establishing British and French patrol zones around Spain ( with a total of 60 destroyers and aircraft employed ) to counteract aggressive behavior by submarines . Italy was not directly accused , but had to comply with the agreement and suspend the underwater operations
Nyon Conference
Nyon Conference
Italian submarine Iride