The United States and Iran are due to hold their second round of nuclear talks on Saturday, as what both sides are looking for in a deal begins to take shape.

Iran said it was giving high-level nuclear talks with the U.S. on Saturday "a genuine chance", after Trump threatened bombing if discussions failed.

Formally called the Joint Comprehensive Plan of Action (JCPOA), the nuclear agreement was signed in July 2015. It was a landmark accord reached by Iran and six world powers (P5+1). Besides the US, these countries included Russia, China, Britain, France and Germany.