The Iranian-Saudi showdown for the leadership of the Islamic world is heating up. The Saudi Arabian government issued a warning against pilgrims staging demonstrations during this year’s hajj, which runs from November 25-29. Although Iran was not specifically mentioned in the Saudi statement, Tehran replied it would take “appropriate measures” if Iranian pilgrims were interfered with in any way.

The strain in Saudi-Iranian relations over the hajj is just the latest manifestation of the Sunni-Shiite conflict across the Islamic world. The dispute between the two main branches of Islam is a political one concerning the Prophet Muhammad’s line of succession. The minority Shiites number about 200 million, of whom 70 million live in Iran, the champion and heartland of Shiiism where the most important Shiite religious sites are located.

While Shiite-Sunni relations in most Islamic countries are good, the Wahhabi doctrine that rules Saudi Arabia contains “a virulent hatred” for Shiites, consigning them to heretic status. When one of Shia Islam’s most holy sites, the Shrine of the Two Imams, was bombed in Iraq in an al Qaeda-organized strike in 2006, one observer noted “radical Wahhabi clerics applauded the destruction.”

After that bloody incident, the ensuing sectarian violence in Iraq saw thousands of Sunnis killed and tens of thousands flee as refugees. Besides nearly engulfing Iraq in a civil war, the blatant anti-Shiite terrorist act almost triggered an Islam-wide religious conflict that would have approximated the European religious wars of the seventeenth century.

As it is, there is conflict enough between Islam’s two main branches. Last January in Nigeria, fighting between a radical Shia group and Sunnis in Zaria left five dead. The radical Shiite movement in Nigeria was founded after the Iranian Revolution in 1979 and has as its goal the establishment of a Shiite Islamic state in Africa’s most populous nation. Since the Sunnis oppose this, wanting to impose their version of an Islamic state, there have been assassinations of leaders on both sides as well as riots and battles.

At the other end of the Islamic world, Pakistan is a hotbed of Sunni-Shiite sectarian violence. An anti-Shiite political party, Sepah-e-Sahaba Pakistan, even tried to have Shiites legally declared infidels but was unsuccessful. A breakaway terrorist faction, the Lashkar-e-Jhangvi, patronized by Saudi Arabia, simply kills Shiites, targeting their mosques and religious leaders. Al Qaada and the Pakistani Taliban, also deadly haters of the Shia, share in these sectarian murders.

Pakistan’s Shiites, who constitute 20 per cent of the country’s 160 million people, retaliated by forming their own terrorist organization, Sepah Mohammad, which murders Sunnis. One analyst predicts there may be more than 800 such sectarian killings in Pakistan by the end of this year, the number increasing almost every year.

In neighboring Afghanistan, thousands of Shia Afghans, principally from the Hazara ethnic group, were murdered by the Taliban in the 1990s. The Shias were the only group the Taliban treated worse than women. As author Ali A. Allawi writes in his book, The Crisis Of Islamic Civilization: “Fatwas by radical Wahhabi clerics have justified mass murder against the Shia in Iraq, Pakistan and Afghanistan.”

Like the United States and the Soviet Union in the Cold War, Saudi Arabia and Iran support their factions in all these conflicts. But it is in Yemen where the two Islamic states are said to be fighting an outright “proxy war.”

In northern Yemen, the Shiite Houthi tribes, supported by Iran, are fighting the Yemeni government, which is backed by large-scale Saudi assistance. The Iran-backed Houthis, who make up 40 per cent of Yemen’s population, are accusing the central authorities of favoring the country’s Sunnis and are suspected of wanting to be ruled by their own Shiite imams.

Since the Shiite insurgency, in which about 1,000 have died, is taking place on Saudi Arabia’s border, the Saudis fear the area may become a launching pad for attacks on the kingdom. A recent Houthi raid into Saudi territory that resulted in a dead Saudi border guard justified this fear. The Saudis responded with warplane raids on Houthi positions and massed troops on the Yemeni border, intensifying the fighting.

Iran is helping its Houthi Shiite brethren with arms shipments and Shiite Hezbollah fighters from southern Lebanon. Yemeni authorities recently seized one ship loaded with Iranian weapons destined for the battlefield. Diplomacy has also not been neglected. Iran’s foreign minister has said he will travel to Yemen in an effort to mediate the conflict. One analyst sees this as a “huge setback to Saudi prestige”, as the government Saudi Arabia is backing is “now compelled to seek Tehran’s good offices.”

According to one observer, the Saudis have actually been worried about the hajj since 1981. In the past, Iranian Shiites have turned this annual religious pilgrimage that attracts about three million Muslims from around the world into a political event. In the early 1980s, Iranian pilgrims staged a demonstration in Medina close to Muhammad’s burial shrine. In 1987, more than 400 people died in clashes between Saudi police and Iranian Shiites outside the Grand Mosque in Mecca.

The Saudi cabinet’s statement indicates trouble is a distinct possibility at this year’s hajj. In their religious rivalry, Iran would have a vested interest in disrupting the pilgrimage and embarrassing Saudi Arabia as the keeper of the holy places. Saudi prestige is already suffering among many Muslims for its perceived dependency on the West. Violence and accusations against Saudi Arabia of maltreating pilgrims would promote Iran’s interests but run the danger of inflaming Iranian-Saudi hostility, perhaps past the breaking point.