The reason is simple "CORRUPTION", they could have easily got access to any technology/fuel from any of the NSG, but they have now committed themselves just to US/Aussie combine, its obvious there are a lot of scam money involved.
The deal is worth $200 billion, the commision can range from 1% to 4% (which is considered legal), so just calculate the amount these fellows are now planning to swindle, in the name of national energy security.
