Iranian President Mahmoud Ahmadinejad said Saturday that the Islamic Republic would soon announce "very major" advances in its nuclear program.
A Revolutionary Guard commander also said Iran would respond to military action by sending thousands of missiles at Israel and U.S. bases.
Ahmadinejad was speaking on the 33rd anniversary of the Islamic revolution that toppled the U.S.-backed Shah. Tens of thousands of Iranians joined state-organized rallies to mark the occasion.
"In the coming days, the world will witness Iran's announcement of its very important and very major nuclear achievements," Ahmadinejad told a crowd at Tehran's Azadi (Freedom) Square in a speech relayed live on state television.
Demonstrators carrying Iranian flags and pictures of Supreme Leader Ayatollah Ali Khamenei chanted "Death to Israel" and "Death to America."
Ismail Haniya, who heads the Islamist Hamas administration in the Gaza Strip, also attended the ceremony.
Ahmadinejad gave no details of how Iran's nuclear work, which Tehran says has only peaceful purposes, has progressed.
The United States and Israel, a country which Iran does not recognize, have not ruled out military action if sanctions fail.
Iran has warned of a "painful" answer, saying it would hit Israel and U.S. bases in the Gulf as well as block the vital Gulf oil shipping route through the Strait of Hormuz.
"If attacked by the Zionist regime (Israel), we will turn it to dust," said a Revolutionary Guards commander, Mohammad Shirdel, semi-official Fars news agency reported Saturday.
"Thousands of our missiles will target Israel and the 40 bases of America in the region," he added.
West tightens sanctions
The nuclear dispute has fueled tension as the West tightens sanctions. The European Union has agreed to ban Iranian oil imports by July and to freeze the assets of Iran's central bank.
Its measures reinforce those imposed by the United States as the West tries to force Tehran to return to talks before it produces enough nuclear material for an atomic bomb.
Neither side has shown much appetite for compromise. Iran says it will fight EU sanctions with counter-measures and its parliament plans legislation to ban oil exports to the EU.
Iranian officials brush off the impact of sanctions, while also proclaiming that Iranians will endure any hardship in support of their country's right to nuclear technology.
"I am saying openly that if you (the West) continue to use the language of force and threat, our nation will never succumb to your pressure," Ahmadinejad said.