Jan Techau, The Politics of 2 Percent: NATO and the Security Vacuum in Europe, su carnegieeurope.eu, Carnegie Europe, 2 settembre 2015. URL consultato l'11 luglio 2018.
«"A month before [the alliance’s summit in Riga in 2006], Victoria Nuland, then the US ambassador to NATO, called the 2 percent metric the "unofficial floor" on defense spending in NATO. But never had all governments of NATO’s 28 nations officially embraced it at the highest possible political level – a summit declaration."»
