Dropmire is a secret surveillance programme by the National Security Agency aimed at surveillance of foreign embassies and diplomatic staff, including those of NATO allies. The programme's existence was revealed in June 2013 by whistleblowerEdward Snowden in The Guardian newspaper.  The report reveals that at least 38 foreign embassies were under surveillance, some of which as far back as 2007.
Earlier in the month, The Guardian had reported that the NSA spied on diplomats during the 2009 G-20 London Summit, but no precise program name was revealed at the time. 
Diplomatic spying by the United States had been revealed as far back as 2010, when it was revealed that US agencies had spied on UN chief Ban Ki-moon – at the time, it was not known that this had been done as part of a systematic program.