US intelligence agencies discovered the Israeli government leaked details of the US-Iran nuclear negotiations and coordinated efforts with Jewish-American groups to undermine the talks, it is claimed.
The NSA - which has faced intense criticism for tapping the phone conversations of its allies in recent years - reportedly eavesdropped on the conversations of Israeli Prime Minister Benjamin Netanyahu and his advisers as the talks progressed.
According to the Wall Street Journal, Mr Netanyahu was caught on tape negotiating with undecided congressman and senators about what it would take to get them to vote against the nuclear deal agreed in July this year.
A US intelligence official who has reportedly heard the intercepts said Israeli officials were heard asking the undecided American lawmakers questions such as “How can we get your vote? What’s it going to take”.
The officials told the Wall Street Journal that it appeared Israeli negotiators were confident they would have enough votes to block approval of the deal in Congress.
Israel used its own spies to gather information about the progress being made during the negotiations which brought Iran back into the diplomatic fold after 30 years of isolation.
Israel has said the move threatens their security as Iran is one of many countries in the Middle East who do not recognise Israeli sovereignty and has threatened to “wipe them off the map”.
America's top 11 fears
America's top 11 fears
Fracturing of Iraq
Violence in Afghanistan
Instability in Egypt
Political violence in Turkey
Increased tensions between Israel and Palestine
Violence and instability in Libya
Political instability in European Union resulting from migrants and refugees
Nuclear war with North Korea
Cyber attack on critical infrastructure
Mass casualty terror attack on the US
Intensification of civil war in Syria
Israeli officials have denied targeting US negotiators but NSA intercepts are reported to have shown the country was monitoring the talks in Switzerland.
In the transcripts of the intercepted conversations all American citizens were marked as “US person” and US corporations were identified as “US organisation” to protect their anonymity.
The NSA and its Israeli counterpart, Unit 8200, have had close links in the past.
The American organisation helped Israeli expand its electronic spying systems to monitor its regional enemies and the information was then shared with the US.
The two are believed to be still working together at the start of the Obama administration but revelations by Edward Snowden about American surveillance have raised tensions in recent years.