Reza Pahlavi, eldest son of Iran's ousted Shah, sees opportunity as US officials turn their attention to his country's Islamic regime as a possible next target in Washington's relentless campaign against terrorism.

For the past 18 months, Iran's clerical rulers -- beset by opposition at home -- have watched uneasily as US military power has surrounded them after victories over an Islamist regime in Afghanistan and Iraqi dictator Saddam Hussein.

They now find themselves accused by Washington of developing nuclear weapons and harboring members of the al-Qaeda Islamist militant group, allegations they insist are untrue.

"The momentum today has swung in a very clear way in the direction of change in Iran," said Pahlavi, 42, whose father, former shah Mohammed Reza Pahlavi, was forced from power in the 1979 Islamic revolution.

But as US leaders debate what to do with Iran, they might discover they have few options.

Experts say internal political and religious currents may play a greater role in Iran's future than US pressure or the efforts of exile groups. Events in Iraq, now controlled by the United States and Britain under UN auspices, also could influence Iran's destiny, they say.

US pressure on Iran has intensified since President George W. Bush named Tehran's Islamic rulers part of an "axis of evil" with Saddam and North Korea's communist rulers in January 2002.

Questions over how Iran has handled members of al-Qaeda have torpedoed tentative steps towards greater dialogue between Tehran and Washington, and prompted some US lawmakers to propose support for Iranian resistance groups and funds for pro-democracy broadcasts into the country.

The Washington Post reported Sunday that Pentagon officials are advocating trying to foment a popular uprising to topple Iran's government, and the State Department may accept that approach if Iran does not take steps to crack down on al-Qaeda.

Key lawmakers, however, ruled out US military action similar to the massive armed assault on Iraq which overthrew Saddam last month, saying it was not necessary.

"There are a lot of people in Iran who truly like us," Senator Richard Lugar of Indiana told CBS.

With Washington's victories against Islamist radicals and reformists inside Iran intensifying their pressure on the clerical regime, Pahlavi sees US support as a crucial element that might tip the balance in favor of the secular democracy he supports. "Iranians at home are deeply and positively impacted by such changes," he said. "It can only contribute to stability."