Iranian Foreign Minister Mohammad Javad Zarif and US Secretary of State John Kerry were awarded a prestigious prize on Monday for their efforts in clinching a nuclear deal between Iran and six world powers.

Members of Chatham House this year voted for Zarif and Kerry, praising their crucial role in successfully negotiation the nuclear agreement, known as JCOPA.

The historic agreement gave sanctions relief to Iran, and in return the Islamic Republic has limited some of its nuclear program activities. The deal went into effect in January this year.

The deal is known as an end to one of the most intractable diplomatic stad-offs in international affairs in the 21st century.

Israeli Prime Minister Benjamin Netanyahu lobbied against the agreement, but failed at impeding international efforts to achieve this end. The majority of US Republican party members also opposed the deal.

According to the London-based Chatham House, Royal Institute of International Affairs, the prize is awarded annually “to the person, persons or organization deemed by members… to have made the most significant contribution to the improvement of international relations in the previous year.”

“Kerry and Zarif’s leadership and commitment… were imperative to sustaining and driving the negotiations to their successful conclusion, while overcoming enormous technical complexity, entrenched domestic opposition in the United States and Iran and three decades of intense hostility between their two countries,” the think tank said.