(3.Juli 2014) My translation of the announcement (in Dutch) of the launch (I translated as literally as possible):

With the launch of the Joint Sigint Cyber Unit (JSCU), the General Intelligence & Security Service (AIVD) and the Military Intelligence & Security Service (MIVD) take an important step in better protecting the national security and our digital networks against threats, and at the same time better support our soldiers on missions. A successful cooperation requires proper arrangements. These arrangements are laid out in a covenant [.pdf, in Dutch] that is signed by the Minister of the Interior and the Minister of Defense.

(3.7.2014) The joint unit is specialized in Signals Intelligence (Sigint) and Cyber. Sigint includes information collection from (tele)communications. Cyber is a collective term for various activities related to computer networks and data streams. Think of mapping the internet landscape in a (new) mission area, informing partners about a dangerous computer virus or hacking a terrorist website that threatens national security.

The government is committed to further cooperation between the AIVD and the MIVD.