Iranian security forces clashed with supporters of Iran's opposition leader Mirhossein Mousavi in Tehran on Wednesday when a rally marking the 30th anniversary of the storming of the U.S. embassy turned violent

The crackdown showed no compromise from the leadership. Supreme Leader Ayatollah Ali Khamenei says it is a crime to question the June 12 vote which secured the re-election of President Mahmoud Ahmadinejad.

Defeated presidential candidates Mousavi and Mehdi Karoubi say they are committed to reform.

Following are some questions about the future of the reform movement in Iran:

HOW SIGNIFICANT WERE WEDNESDAY'S PROTESTS?

Many Iranians were frightened to join the latest protest after harsh warnings from the clerical establishment and security forces, particularly the Revolutionary Guards that quelled post-election protests.

By contrast, the June election plunged Iran into its deepest internal crisis since the 1979 Islamic revolution and the opposition said more than 70 people were killed in ensuing protests. Officials say half that number were killed.

Harsh sentences issued by the judiciary for jailed protesters prevented some supporters of Mousavi and Karoubi from joining the latest anti-government protest. However, there is political will for the demonstrations to continue.

DO SUCH DEMONSTRATIONS DAMAGE THE CLERICAL LEADERSHIP?

The rough-and-tumble of Iranian politics since the disputed vote has badly dented the clerical establishment's image, both domestically and internationally.

The demonstrations hit the prestige of the ruling clergy, already under international pressure over Iran's disputed nuclear program.

Reformers believe the Islamic Republic must change in order to survive and meet the demands of its predominately youthful population. Hardliners clearly have no intention of yielding to such demands.

WHAT SUPPORT DO OPPOSITION LEADERS HAVE?

Iranian opposition leaders still enjoy the support of many Iranians, who want a freer country. But it is unclear whether people's power will work in Iran.

Opposition leaders have not abandoned their fight for free expression and the rule of law. They have repeatedly pledged to press ahead with efforts to reform the Islamic state.

Mousavi and Karoubi were both very close to the late founder of Iran's revolution, Ayatollah Ruhollah Khomeini, and their revolutionary credentials cannot be ignored.

Some relatives of Khomeini, including his grandson Hasan, have angered hardliners by openly supporting opposition leaders.

HOW DIVIDED IS THE CLERICAL LEADERSHIP OVER TIES WITH THE

WEST AND THE NUCLEAR PROGRAMME?

Iran's top authority Khamenei has the last say on all state matters, including Iran's nuclear program and its relations with the West.

Opposition leaders within the clerical leadership have never challenged Iran's system of clerical rule, even if many of their supporters are seeking broader change.

Reformists are in favor of improving ties with the West but echo Iran's official stance over the country's nuclear program, saying it is Iran's right to have the technology.

(Writing by Parisa Hafezi; Editing by Charles Dick)