Iran wants the world's attention to shift away from its controversial nuclear programme as soon as possible, but the International Atomic Energy Agency (IAEA) is not in any hurry.
"This is not over yet. It has not started yet," IAEA Director General Yukiya Amano says about the work that lies ahead for his nuclear inspectors.
Over the past weeks, Iranian engineers have been racing to dismantle nuclear equipment, so that Iran and six world powers can start implementing a broad nuclear deal as soon as possible early next year.
On implementation day, IAEA inspectors are set to confirm that Iran has scaled down its nuclear programme, while the United States, the European Union and the United Nations are to lift sanctions that have been strangling the Iranian economy.
However, the start of the nuclear deal - marking the end of over a decade of negotiations - will not stop the IAEA's close scrutiny of Tehran's array of atomic installations, Amano told dpa recently at the IAEA headquarters in Vienna.
"This will last for a long time," the Japanese IAEA chief said.
When Iran closed the deal with the United States, Britain, France, Germany, Russia and China in July, it agreed to an unusually intrusive inspection plan that will be phased out only after 15 years.
"This is the most powerful verification tool" that the IAEA has in place anywhere in the world, Amano said.
"Iran's nuclear issue has a very complicated history, and confidence is lacking.
"Before 2003, they had coordinated efforts to develop a number of technologies relevant to weapons," Amano said.
The IAEA has concluded its probe of these past nuclear weapons research and development projects, finding that they have now ended.
Now it will have to check that the Islamic regional power honours its side of the agreement and does not use its civilian atomic infrastructure for making nuclear weapons.
The IAEA's nuclear experts will have to monitor Iran's many far-flung nuclear sites, from an uranium mine near the Arab Gulf coast in the south to the uranium enrichment plant in Natanz, 1,000 kilometres to north.
"It is a very big historic challenge for us," the nuclear agency's chief said.
IAEA inspectors would be able to find out very quickly if any nuclear materials were misused for weapons at any of these facilities, Amano said.
At the same time, the Iran nuclear deal will allow them to follow up any hints of secret nuclear facilities in the future.
"If they try to hide something, we normally find indications somewhere and start to ask questions," Amano said.
The inspections under the Iranian nuclear deal will require significant input of money and staff from the IAEA.
The nuclear agency will need 9.2 million euros (10 million dollars) a year to finance the effort, equivalent to 7 per per cent of its total inspection budget last year.
"We do not have the full amount yet," Amano said.
The IAEA's most immediate task is to verify the steps that Iran has to undertake before the start of the nuclear deal, which could take place in late January, according to Iranian officials.
For example, nuclear inspectors will take uranium samples and analyze them at a laboratory near Vienna, to make sure that the material's purity is low as declared by Iran, in contrast to the high grades needed for nuclear weapons.
"We don't take anything at face value," Amano said.