Der Spiegel reports that documents leaked by Edward Snowden indicate that Britain's GCHQ appears to have been responsible for a recently disclosed breach of Belgian telco Belgacom (h/t Graham Cluley).
Three slides from a top secret GCHQ presentation regarding "OP SOCIALIST" state, "Scoping session conducted -- main focus to be on enabling CNE [computer network exploitation] access to BELGACOM GRX Operator. Ultimate Goal -- enable CNE access to BELGACOM Core GRX Routers from which we can undertake MiTM [man-in-the-middle] operations against targets roaming using Smart Phones."
As Graham Cluley notes, the goal appears to have been to spy on Belgacom International Carrier Services, which provides wholesale services around the world to operators worldwide -- including those in Syria and Yemen.
When contacted by Der Spiegel, GCHQ declined to comment.