This April 2012 training presentation produced by Navy Information Operations Command Maryland states that “the next major conflict will start in cyberspace”: see the Der Spiegel article The Digital Arms Race: NSA Preps America for Future Battle, 17 January 2015.
This 23 Febrauary 2010 post from the internal NSA newsletter SIDToday describes advances in the agency’s capabilities against 4G signals, described as “a very high priority for NSA and the Intelligence Community”: see the Intercept article Operation Auroragold: How the NSA Hacks Cellphone Networks Worldwide, 4 December 2014.
This document, produced by the NSA and the US military’s Joint Functional Component Command – Network Wardare, provides a briefing on, and classification guide to, the highly sensitive group of “core computer network operations secrets” codenamed SENTRY EAGLE: see the Intercept article Core Secrets: NSA Saboteurs in China and Germany, 10 October 2014.
This 23 November 2004 decision memorandum from then-NSA Director Keith Alexander gives the initial go-ahead for the agency’s ICREACH system: see the Intercept article The Surveillance Engine: How the NSA Built Its Own Secret Google, 25 August 2014.
This ODNI briefing from 15 May 2007 describes the rationale for ICREACH and the scale of metadata sharing that was envisioned: see the Intercept article The Surveillance Engine: How the NSA Built Its Own Secret Google, 25 August 2014.