Barack Obama hailed United Nations secretary general Ban Ki-moon as a "good friend" after the two had sat down in the White House in April to discuss the issues of the day: Syria and alleged chemical weapons attacks, North Korea, Israel-Palestine, and climate change.

But long before Ban's limousine had even passed through the White House gates for the meeting, the US government knew what the secretary general was going to talk about, courtesy of the world's biggest eavesdropping organisation, the National Security Agency.

One NSA document – leaked to the Guardian by whistleblower Edward Snowden just a month after the meeting and reported in partnership with the New York Times - boasts how the spy agency had gained "access to UN secretary general talking points prior to meeting with Potus" (president of the United States). The White House declined to comment on whether Obama had read the talking points in advance of the meeting.