there is no question that the attacks on Belgacom and others came from the UK and more precise from the GCHQ bases
but these bases although on UK territory are not necessarily totally under the control of the UK government because they are paid and led by also the NSA while people from the other partners are also working on these bases
so the question is more complicated than at first sight
the 5 allies after the second world war formed an intelligence alliance because they also discovered that the British and other intelligence agencies were deeply penetrated by Russian spies during the second world war (while they were concentrating on the nazis and saw the russians as allies) and needed the intelligence from the USA to help them keeping their secrets secret from the Russians which weren't the allies anymore but became the new enemies because they were occupying eastern europe and installing a strange form of people democracy
so the real question is if the new europe can have a place in the new 6 eyes intelligence coalition ?
In De Standaard they refer to the story about the spying on Merkel and the diplomatic row that followed but it now seems that the story is crap and that there are doubts about these specific documents so you can say that Di Rupo was only cautious because in Germany they are now embarrassed that they have made such a row with so little real evidence