The revelation could well prompt new international efforts to get Iran to curtail, or abandon its nuclear research program. Iranian officials insist the country’s nuclear research is intended solely for civilian applications, but US and EU leaders are convinced that Tehran strives to develop nuclear weapons.

Against this backdrop, top Iranian leaders are making doctrinal adjustments with the aim of reinforcing their domestic authority. The clearest signal of a shift came March 21, Persian New Year, when the country’s supreme leader, Ayatollah Ali Khamenei, gave an unprecedented address that seemed to court the support of secular-minded nationalists, as well as minority groups.

Traditionally, Ayatollah Khamenei’s New Year’s address hasn’t been a forum for major policy announcements. Instead, the supreme leader has tended to use the speech to promote pious living. This year, however, it was an entirely different story. The normal platitudes about adhering to a traditional lifestyle were largely absent. Ayatollah Khamenei lashed out at foreign powers, threatening retaliation against those states trying to thwart Iran’s ambitions. He then went on to urge national unity to counter efforts to force Iran to abandon its present nuclear course.

"This year is the year of ‘national unity’ and ‘Islamic solidarity,’ which means unity and harmony among all members of our nation, including various ethnic and religious groups, and different national factions," Ayatollah Khamenei said. He went on to call for "solidarity among all Muslims and brotherly relations and unanimity among all members of the Islamic nation, including followers of different Islamic schools of thought."

The speech, watched by millions of Iranians, also marked the first occasion since the 1979 Islamic revolution during which a top-ranking cleric spoke about Mohammad Mosadegh -- Iran’s nationalist leader who nationalized the oil industry and was ousted in a US-engineered coup in 1953 – in a favorable light. In his address, Ayatollah Khamenei twice referred to the former nationalist prime minister as "Doctor Mosadegh" – a sign of respect.

During the Islamic republican era, Iranian religious leaders have treated Mosadegh’s historical legacy with extreme caution, with some even vilifying him. The hesitant attitude seemed driven by concern that Mosadegh’s legacy posed a threat to the Islamic revolution’s aims and ideals. Although a popular figure for many Iranians, the country’s Islamic leadership has never sanctioned any effort to memorialize him. To this day, there is not a single street or square named after him.

Overnight after Ayatollah Khamenei’s speech, "national unity" became the bywords of the political elite. Thousands of colorful banners and posters quickly went up throughout Iran emblazoned with the slogans "national unity" and "Islamic solidarity." State-controlled mass media outlets devoted a considerable amount of air time to promoting the national-unity theme.

At the same time, state-run television broadcast programming that touted the glories of the ancient Persian Empire, as well as recalled great nationalist uprisings. Such programming was rarely seen on Iranian channels prior to the Supreme Leader’s New Year’s address.

In connection with the broadcast campaign, pro-government commentators condemned the movie "300," recently released by the Hollywood Studio Warner Bros. The movie is a fictionalized account of the Battle of Thermopylae in 480 B.C., during which Spartan warriors held off a massive Persian invasion force for several days, thus enabling Sparta’s Greek allies to regroup and repel the Persians. Commentators in Iran complained that the movie denigrates Iranians’ Persian ancestors.

The leadership’s national unity campaign hasn’t achieved any tangible results so far, as there has been no discernable upswing in support for the government. If anything, the campaign seems to have disappointed some Iranians, especially those who hoped that the effort to promote national unity would be accompanied by limited steps toward political liberalization. Recently, officials informed the Parties’ House, a semi-official forum for representatives of political parties, that the government had no intention of loosening existing controls on political activity.

Some Tehran analysts believe that the country’s leadership would be willing to make substantive concessions only if the international community managed to significantly increase pressure on Tehran. For now, the government’s grip on power is firm, and officials see no need to cede ground, some experts say.

Any attempt to open up the political system could prompt fierce resistance by Islamic traditionalists, observers add. Highlighting this possibility is the controversy surrounding the anticipated crackdown on women who violate the Islamic dress code. The crackdown, which has almost become an annual rite, is expected to commence on April 21 – the start of the second month in the Persian calendar.

During the crackdown law-enforcement officials patrol cities and towns across the country, issuing verbal warnings to, levying fines against and, in some cases, making arrests of women who flaunt rules governing attire in public.

This year many young women in urban centers, especially in Tehran, have attempted to radically expand the dress code’s boundaries, with some covering their heads only with small strips of fabric instead of the traditional hijab, or wearing trousers that come up to knee level. Far-right groups have been clamoring for months for a crackdown, and the government has announced repeatedly that on April 21, strict enforcement will begin.

The surprising element for some Tehran observers is the fact that a behind-the-scenes power struggle raged over how the crackdown would be carried out. Initially, authorities seemed prepared to exclude the more radical Islamist elements, especially members of the Basij militia, from enforcing the dress code. The Basij is a paramilitary force directly subordinate religious leaders. Along with the Revolutionary Guards, the militia has traditionally acted as an enforcer of Islamic orthodoxy.

On April 16, Gen. Mahmmod Salarkia, a top-ranking officer of the country’s main domestic law-enforcement agency, known as NAJA, announced that Basij militiamen would not be involved in efforts to enforce the dress code. Many observers linked Salarkia’s announcement to Ayatollah Khamenei’s New Year’s address.

Yet, the next day, another top NAJA official, Gen. Ahmad Roozbahaee, who heads the agency’s anti-vice department, contradicted his colleague, saying that Basij militiamen would indeed be empowered this year to "confront the poorly-clad." The sudden reversal may have been the result of forceful pressure exerted by hardliners and social conservatives after the initial announcement.