Iran and the rest of the world CANNOT trust the US. She breaks agreements and contracts at will.
The only country that has criminally used nuclear bombs against civilian people, the US, wants to maintain her ability to bully and blackmail other nations to subjugate themselves to her will.
I am strongly against any proliferation of nuclear armament but the US is NO trustworthy part to any agreements and should be the first one to dismantle her nuclear bombs !! The EU should be the proper partner to any Iranian deal in this matter. Keep the US out of it.