Speaking the day after the United States withdrew from an worldwide agreement on Iran's nuclear programme, the head of the United Nations atomic watchdog agency made it clear that Iran has consistently stuck to its commitments.
The agency was tasked with conducting inspections to verify if Iran is complying with the terms set down by the deal.
Varjoranta, who was in the role for nearly five years, will be replaced by Massimo Aparo, an Italian nuclear engineer.
"The United States will continue to support robust implementation of IAEA inspections in Iran to the full extent of the IAEA's authority", an official at the U.S. mission to the IAEA told AFP on Friday.
According to the statement, Iran "is subject to the world's most robust nuclear verification regime under the Joint Comprehensive Plan of Action (JCPOA), which is a significant verification gain".More news: Rafael Nadal's clay-court run ended by Dominic Thiem
Since the accord was reached in 2015, the IAEA has carried out hundreds of inspections inside Iran.
The 61-year-old Finn became chief inspector of the Vienna-based International Atomic Energy Agency (IAEA) in late 2013 after previously heading Finland's Radiation and Nuclear Safety Authority.
The agency also points to the some 2,000 tamper-proof seals attached to nuclear material and equipment and to the "hundreds of thousands of images captured daily by our sophisticated surveillance cameras", the number of which has nearly doubled since 2013.
Under the JCPOA deal, the US and other world powers agreed to lift some economic sanctions imposed on Iran in return for the latter agreeing to rein in its nuclear program.
The JCPOA - reached by Iran, China, France, Germany, Russia, the United Kingdom, the U.S. and the European Union - sets out rigorous mechanisms for monitoring restrictions placed on Iran's nuclear programme, while paving the way for the lifting UN sanctions against the country.