This GCHQ document from March 2010 presents a checklist of factors analysts should consider before going ahead with an operation to infiltrate a communications network, by physical or other means. Among the concerns raised is the risk that British actions may enable US authorities to conduct operations “which we would not consider permissible”: see the Boing Boing article Doxxing Sherlock, 2 February 2016.
This redacted slide from a 2007 NSA presentation describes NSA operations against the EU embassy in Washington DC: see the Guardian article New NSA leaks show how US is bugging its European allies, 30 June 2013.
This NSA document from 10 September 2010 details operations against foreign embassies, concluding with a glossary of tools and tactics. Earlier versions of this docoument that only contained some of the operations conducted were published in l’Espresso on 5 December 2013 and in Le Monde on 21 October 2013: see the book No Place to Hide, 13 May 2014.
This briefing from 23 June 2010 describes the NSA’s plans for the G8 and G20 summits in Toronto and the extent of Canadian cooperation. Note that redactions have been made to this document that were not present in a version broadcast on television: see the CBC News article New Snowden docs show U.S. spied during G20 in Toronto, 28 November 2013.