In 2009, the Greek Ministry of Defence launched an open tender for €22m worth of submarine battery kits. The invitation to tender included a requirement that 35 per cent of the material used for the batteries must be produced in Greece. The authorities claimed that this was justified on the grounds of national security interests. On 24 November 2009, the European Commission sent a reasoned opinion to Greece stating that the authorities had failed to provide “detailed and reasoned argumentation clearly evidencing that using standard EU public procurement rules would endanger Greek security interests”.