"The GCHQ mass tapping operation has been built up over five years by
attaching intercept probes to transatlantic fibre-optic cables where they
land on British shores carrying data to western Europe from telephone
exchanges and internet servers in north America.
This was done under secret agreements with commercial companies,
described in one document as "intercept partners"."
http://www.guardian.co.uk/uk/2013/jun/21/gchq-cables-secret-world-communica…
Fred