MOSCOW, Oct. 21 (Xinhua) -- Russia has said it is confident that Iran is fulfilling all its obligations under a multilateral agreement on its nuclear program and will not take part in any talks on amending the deal.

Russian Deputy Foreign Minister Sergei Ryabkov made the remarks Saturday at an international nuclear weapons non-proliferation conference here, TASS news agency reported.

Russia is not ready to participate in any talks on amending the Joint Comprehensive Plan of Action (JCPOA), Ryabkov was quoted as saying.

The deal is delicately balanced and any change could cause the collapse of the whole agreement, he warned.

The JCPOA was reached between Iran, the five permanent members of the United Nations Security Council -- Britain, China, France, Russia and the United States -- plus Germany, in July 2015. Under the deal, Iran agreed to halt its nuclear weapon program in exchange for economic aid and lifting of international sanctions.

However, on Oct. 13, U.S. President Donald Trump called for decertifying the agreement, alleging Iran had committed "multiple violations".

Though the decertification would not mean Washington exiting the Iran nuclear deal at the moment, it would open a 60-day window in which the U.S. Congress could reimpose nuclear-related sanctions on Iran.

International Atomic Energy Agency Director General Yukiya Amano said last week that Iran was implementing the JCPOA under a robust verification regime.