Guterres made the remarks in a report on implementation of a UN resolution that endorsed the July 2015 nuclear agreement, which was obtained by The Associated Press.
He hailed the agreement – also known as the Joint Comprehensive Plan of Action (JCPOA) – as the “the best way” to ensure the peaceful nature of Iran’s nuclear program.
The UN chief pointed to US President Donald Trump’s refusal to certify Iran’s compliance with its obligations under the JCPOA and warned that Washington’s decision has created “considerable uncertainty” about the future of the deal.
However, he expressed optimism about US commitment to the deal, saying, “I am reassured that the United States has expressed its commitment to stay in the Joint Comprehensive Plan of Action for now.”
“I encourage the United States to maintain its commitments to the plan and to consider the broader implications for the region before taking any further steps,” he said.
Iran and the five permanent members of the United Nations Security Council – the United States, France, Britain, Russia and China-- plus Germany signed the nuclear agreement on July 14, 2015 and started implementing it on January 16, 2016.
Under the JCPOA, Iran undertook to put limits on its nuclear program in exchange for the removal of nuclear-related sanctions imposed against Tehran.
Eight reports by the International Atomic Energy Agency (IAEA) have confirmed Iran’s full compliance with the agreement.
However, Trump delivered an anti-Iran speech on October 13, in which he said he would not continue to certify Iran’s compliance with the terms of the JCPOA, reached under his predecessor, Barack Obama, and warned that he might ultimately terminate the agreement.
The other parties to the accord – Britain, Germany, France, Russia, China and the European Union – have all reaffirmed their commitment to it and urged the United States not to back out.
Guterres said Iran may be defying a UN call to halt ballistic missile development even as it complies with the nuclear deal with six world powers.
Elsewhere in his report, he pointed to a letter sent by France, Germany, Britain and the US in which they claimed that Iran’s Simorgh Space Launch Vehicle launched on July 27 is “inherently capable of delivering nuclear weapons.”
The UN chief, however, pointed to Russia's contention through a letter on August 16 that the Security Council resolution only includes a “call” for Iran to forgo missile activities, not a prohibition.
Guterres also said Iran's argument that Simorgh Space Launch Vehicle was “part of a scientific and technological activity related to the use of space technology.”
Iran also said its “military capabilities, including ballistic missiles, have not been designed to be capable of delivering nuclear weapons and thus are outside the purview of the Security Council resolution,” the UN chief said.
During the meeting of the Security Council on September 8, “there was no consensus among council members” on how the launch of Simorgh satellite-carrier was related to the JCPOA, Guterres’ report pointed out.