One of former NSA contractor Edward Snowden's most shocking revelations was that the US National Security Agency conducts almost-unrestricted surveillance on the heads of state of allied countries; this sparked a major scandal in Germany.

The US National Security Agency (NSA) shared intelligence with its Israeli counterparts from SIGINT National Unit (ISNU), the newest discoveries from Edward Snowden's leaked archives reveal. Notably, US law prohibited the agency from doing so, due to the ISNU's use of targeted assassinations.

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The two agencies started working together around the time of the Lebanon War in 2006 using a loophole, with the NSA feeding the intelligence on alleged terrorists via the Office of the Director of National Intelligence, according to an article in SIDToday – an internal publication of the NSA. The info reportedly allowed Israeli Defence Forces to launch precise strikes on Hezbollah during the war, but they still wanted to get all the intelligence they could and be exempted from the US laws banning them from obtaining it.

In 2009 the two agencies signed a memorandum of understanding that basically gave ISNU the access to the intelligence it sought. Israelis could look though all of the NSA's raw surveillance data, including American citizens, with only one exception – US officials. Still, even on this matter the NSA relied on ISNU honour as it was reportedly instructed to "destroy upon recognition" the surveillance data, which involved such officials.

One of the documents leaked by Snowden suggested that the ISNU had "heavily relied" on the data that the NSA fed them, as they were seeking information about the condition and location of Hezbollah forces, as well as geolocation data and information regarding Iran's activities.

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The NSA found itself in the middle of an international scandal in 2013 after Snowden leaked thousands of classified documents detailing the NSA's surveillance. It was revealed that the agency had massively spied on US and foreign citizens, as well as on foreign heads of state, even allies. The NSA also developed a number of spy programs for hacking into all kinds of devices with the aim of using them for surveillance purposes.

The US charged Snowden with espionage and the theft of government property, but he managed to flee to Russia, where he received asylum.