This internal NSA document from April 2013 provides a progress report on projects where the NSA’s Signals Intelligence Directorate (SID) strategy involves a foreign partner. A paragraph on Sweden indicates that GCHQ’s participation in Quantum malware operations “may be in jeopardy” but that making the project a joint US-Swedish one has been “NSA’s goal all along”: see the SVT article FRA part of top-secret hacker project, 11 December 2013.
On 11 December 2013, the Swedish state TV channel SVT broadcast a 50-minute documentary The Snowden Documents and Sweden.
An information paper dated 18 April 2013 describes the close relationship between US, UK and Swedish signals intelligence agencies. A short extract from a second document dated 6 June 2006 emphasises the political sensitivity of the relationship: see the SVT article Dokument avslöjar: FRA:s hemliga avtal med US, 8 December 2013.