Russia announced the start of nuclear fuel deliveries to Iran's Bushehr atomic power plant on Monday.
"What do nuclear fuel supplies give Iran? They give an entirely new quality [to its nuclear program]," said Avigdor Lieberman, the minister of strategic affairs.
He said the creation of nuclear weapons in Iran was a "matter of political will" and that "transition from the civilian nuclear energy path to a military one is a matter of a few months only."
Israel, which regards Iran's nuclear ambitions as the main threat to its existence, has questioned the findings of the recently published American National Intelligence Estimate, which asserted that Tehran ceased developing nuclear weapons in 2003.
Lieberman had previously said that one must read the "fine print" in the American report.
"Unlike the Security Council's decision, (the report claims) that they are continuing to enrich uranium. Is there another UN Member Nation in the world that so often declares its intention to destroy Israel?" he asked.
Iran's first nuclear power plant in Bushehr will not be commissioned before the end of 2008, the Russian contractor building the $1 billion plant said on Thursday.
"I promised to verify the timeframe for the construction of the Bushehr nuclear plant, but I can say with certainty that the plant will not be commissioned before the end of 2008," said Sergei Shmatko, the head of state-controlled Atomstroyexport.
He said containers with fuel sealed by IAEA [International Atomic Energy Agency] inspectors had been delivered to the site and placed in a special storage facility subject to international safety monitoring.
The start of deliveries followed months of delays to the plant's construction, which Moscow attributed to payment arrears, but Iran blamed on pressure from Western nations, who suspect the Islamic Republic of plans to build nuclear weapons.
The United States and other Western powers have pushed for measures to force Tehran to halt uranium enrichment, which is used in both electricity generation and weapons production.
Russia's Foreign Ministry said the start of nuclear fuel supplies to Iran means the country has provided additional written guarantees that the fuel will be used solely for electricity generation.
Under a Russian-Iranian agreement on Bushehr, nuclear fuel deliveries to the plant start about six months ahead of its commissioning. The ministry said supplies would continue into February 2008.
Spent Russian fuel is to be re-exported for reprocessing and storage, according to the agreement. In Iran, the nuclear fuel will be under control of the United Nations nuclear watchdog, the International Atomic Energy Agency, the ministry said.