12.01.17 Financial Times UK

1. 01.01.17 The Guardian

1.1. 31.12.16 Der Spegel

1.1.1. Named Government Source

1.2. Reporter David Crouch

2. Date Unknown Unnamed Security Expert

3. 12.05.17 Russia Today

3.1. 12.04.16 Berosvki News

3.1.1. Date unknown. Unnamed Security

3.2. Reporter Ivan Gorbachov

4. 24.12.16 PM David Cameron

4.1. "industry sources"