Russian and Iranian engineers are loading uranium fuel into Iran's nuclear power plant at Bushehr.
Bushehr is Iran's first nuclear power plant and is located in the southwest part of the country.
John Parker, a Russia and Iran expert at the National Defense University (expressing his personal views) says construction of the power plant has taken a long time.
"It was started by the German Siemens plant - it had the contract with the Shah's government back in the 1970s and worked on it from 1974 to 1980 when construction was halted because of the Iran-Iraq war," Parker said. "Then the new Islamic Republic government shopped around for a new contractor - had quite a bit of trouble getting anybody who would be interested in doing it."
Parker says under Soviet leader Mikhail Gorbachev, the two sides signed an agreement in 1989 that included a clause on cooperation in nuclear issues and the peaceful use of atomic power.
"With the post-Soviet Russia being in desperate economic straits, there was a great interest on the Russian side in making money anywhere and their nuclear power construction industry was in terrible shape after the Chernobyl disaster of 1986. So negotiations began between independent Russia and the Islamic Republic around 1992," said Parker.
"They signed a contract to build Bushehr in October 1995. It was supposed to take 55 months to finish, which meant that it should have been wrapped up around spring of the year 2000. So it's roughly 10 years behind schedule. It's a 1,000 mega watt power generating nuclear plant," he added.
On August 21, engineers began loading fuel into Bushehr - the first step in making it a fully-operational electricity generating plant.
Greg Thielmann is with the Arms Control Association, a private research firm.
"The Russians are providing the low enriched uranium and also committed to removing the spent fuel which is very crucial to non-proliferation concerns, since it can therefore not be used for ill purposes by the Iranians afterwards," said Thielman. "And it will be under the International Atomic Energy Agency inspection process - so that should render it safe from any contribution to a nuclear weapons program."
John Parker says it will take time before Bushehr generates electricity.
"There are several stages before it actually begins generating electricity. They load the fuel, they have to do all sorts of tests - tests take two or three months if everything goes well. So I would not expect any electricity generation until this fall, at the earliest," Parker said.
Iran has always insisted its nuclear program is solely for peaceful purposes. But the international community has been trying to pressure Iran to stop its uranium enrichment program at another facility - Natanz. Highly-enriched uranium could lead to the manufacture of a nuclear weapon. The United Nations Security Council has passed four sets of sanctions against Iran.
Experts say the international community's reaction to the start-up of Bushehr - other than Israel, which called it "unacceptable" - was muted.
Greg Thielmann says the United States has also changed its thinking. He says initially, anything that would increase Iran's competence in nuclear power production was a subject of concern.
"Over time, U.S.-Russian consultations have reassured the U.S. government somewhat that with the understandings reached regarding providing the fuel and removing the spent fuel, that U.S. concerns have been lessened," said Thielman. "I think it is also probably just an acknowledgment over time that Iran had acquired a lot of expertise needed through its uranium enrichment program at Natanz, that any kind of additional knowledge or experience gained at Bushehr was less critical to a potential nuclear weapons program than what it was doing elsewhere."
Experts say the international community's quiet reaction to the start-up of Bushehr does not mean that it will lessen its pressure on Iran to forego its uranium enrichment program.