BUSHEHR, Iran – Trucks rumbled into Iran’s first reactor Saturday to begin loading tons of uranium fuel in a long-delayed startup touted by officials as both a symbol of the country’s peaceful intentions to produce nuclear energy and a triumph over Western pressure to rein in its nuclear ambitions.

The Russian-built Bushehr nuclear power plant will be internationally supervised, including a pledge by Russia to safeguard it against materials being diverted for any possible use in creating nuclear weapons. Iran’s agreement to allow the oversight was a rare compromise by the Islamic state over its atomic program.

Western powers have cautiously accepted the deal as a way to keep spent nuclear fuel from crossing over to any military use. They say it illustrates their primary struggle: to block Iran’s drive to create material that could be used for nuclear weapons and not its pursuit of peaceful nuclear power.

Iran has long declared it has a right like other nations to produce nuclear energy. The country’s nuclear chief described the startup as a “symbol of Iranian resistance and patience.”

“Despite all pressure, sanctions and hardships imposed by Western nations, we are now witnessing the startup of the largest symbol of Iran’s peaceful nuclear activities,” Ali Akbar Salehi told reporters inside the plant with its cream-colored dome overlooking the Persian Gulf in southern Iran.

In several significant ways, the Bushehr plant stands apart from the showdowns over Iranian uranium enrichment, a process that can be used both to produce nuclear energy or nuclear weapons. It also could offer a possible test run for proposals to ease the impasse.

The Russian agreement to control the supply of nuclear fuel at Bushehr eased opposition by Washington and allies. Bushehr’s operations are not covered by U.N. sanctions imposed after Iran refused to stop uranium enrichment. And State Department spokesman P.J. Crowley recently said the Russian oversight at Bushehr is the “very model” offered Tehran under a U.N.-drafted plan unveiled last year.

That proposal — so far snubbed by Iran — called for Iran to halt uranium enrichment and get its supplies of reactor-ready material from abroad.

Western leaders fear Iran’s enrichment labs could one day churn out weapons-grade material. Iran claims it has no interest in nuclear arms, but it refuses to give up the right to make its own fuel.

Iran has some of the world’s biggest oil reserves, but it lacks refinery capacity to meet domestic demand and must repurchase fuel on international markets. Nuclear power is seen as both a goal to meet power needs and an important technological achievement.

The French Foreign Ministry said the Russian deal shows Iran does not need to enrich uranium to benefit from civilian nuclear power.

“This clearly shows that the sanctions do not aim to deprive Iran of its right to develop nuclear energy for peaceful uses,” said the French statement.

But conservative Iranian lawmaker Arsalan Faithipour struck a tone of defiance.

“The startup at Bushehr proved the ineffectiveness of sanctions,” he said.

After years of delays in completing the plant, Moscow now claims that the project is essential to persuading Iran to cooperate with international efforts to ensure it does not develop the bomb.

Over the next two weeks 80 tons of uranium fuel will be moved inside the building and then into the reactor core.

It will be another two months before the heavily guarded 1,000-megawatt light-water reactor is pumping electricity to Iranian cities.