Saudi Arabia's government insists it is not at war with Iran despite its three-week air campaign against Tehran-backed rebels in Yemen, but the kingdom's powerful clerics, and its regional rival's theocratic government, are increasingly presenting the conflict as part of a region-wide battle for the soul of Islam.

The toxic rivalry between Sunni Saudi Arabia and Shiite Iran is playing out on the battlefields of Yemen and Syria, and in the dysfunctional politics of Iraq and Lebanon, with each side resorting to sectarian rhetoric. Iran and its allies refer to all of their opponents as terrorists and extremists, while Saudi Arabian clerics speak of a regional Persian menace.

The rivalry between Saudi Arabia and Iran does not date back to Islam's 7th century schism, but to the 1979 Islamic revolution in Iran, which toppled a U.S.-backed and Saudi-allied monarchy and recast alliances across the region. The standoff worsened after the 2003 U.S.-led invasion of Iraq, which toppled a Sunni-led dictatorship that had long been seen as a bulwark against Iran's efforts to export its revolution.

But even if today's power struggle has more to do with politics than religion, the unleashing of increasingly sectarian rhetoric on both sides has empowered extremists and made the region's multiplying conflicts even more intractable.

Sheikh Mohammed al-Arefe, a Saudi cleric with 12 million Twitter followers and rock star status among ultra-conservative Sunnis, says the Saudi-led coalition launching airstrikes in Yemen is at war with the enemies of Islam. In a sermon viewed nearly 94,000 times on YouTube, he refers to them as "Safawis," a reference to a 16th century Persian dynasty that oversaw the expansion of Shiite Islam.

"It is they, who until today, bow in prayer to shrines," al-Arefe says, referring to the Shiite practice of praying at the tombs of religious figures. Saudi clerics who follow the country's strict Wahhabi doctrine view such rituals as akin to polytheism and advocate the destruction of shrines.

The Saudi government says its coalition of 10 Arab countries is bombing the Houthi rebels in Yemen to restore the country's internationally recognized president, who was forced to seek refuge in Saudi Arabia. The Saudis and the U.S. accuse Iran of arming the Houthis, but Tehran says it only provides aid and political support.

The Houthis are Zaydis, a Shiite offshoot considered close to Sunni Islam, and Yemen's conflict has less to do with sectarianism than with north-south tensions, political corruption and a flawed post-Arab Spring political transition.

Hard-line Saudi clerics like al-Arefe say their problem is not with Zaydis, who make up about 30 percent of Yemen's population, but with the Houthis, who have been "corrupted" by the ideology of "Safawis," a clear reference to Iran.

"Who are the ones killing us in Iraq today, except them? Who are the ones killing us in the Levant today, except them?" al-Arefe said in the same sermon. In Syria, Saudi Arabia is a leading backer of the mainly Sunni rebels, while Iran is a key ally of President Bashar Assad, who hails from the Alawite community, another Shiite offshoot.

In Iraq, Saudi Arabia has had troubled relations with the Shiite-led government that emerged after the U.S.-led invasion, and which enjoys close relations with Iran. Those tensions burst into the open on Wednesday, when Iraqi Prime Minister Haider al-Abadi defended his country's ties to Iran and said he saw "no logic" in the Saudi operation in Yemen.

Asked about efforts to attain a cease-fire in Yemen, al-Abadi said his understanding from the White House is that "the Saudis are not helpful in this. They don't want a cease-fire now."

Saudi Arabia's ambassador to Washington, Adel al-Jubeir, fired back, saying the Iraqi prime minister is entitled to his opinion about Saudi involvement in Yemen but would be better off focusing on Iraq's domestic problems, in particular its need for reconciliation with Sunnis and Kurds.

Fredric Wehrey, a senior associate at the Carnegie Endowment for International Peace, says the war on the Houthis has allowed the kingdom to position itself once again as the defender of Islam, particularly after some conservatives were critical of its involvement in U.S.-led airstrikes against the Islamic State group in Iraq and Syria.

"It did stir a lot of ambivalence and even outright criticism from people who say, 'Well you know, ISIS is bad but at least ISIS is standing up to the Shiites and the Iranian menace,'" Wehrey said.

"Now this war on the Houthis is a godsend to them because they are able to stir up this new Saudi nationalism, this pan-Sunni fervor, and it's to show they are defending the Sunnis... for domestic benefit."

Since 1979, Iran has also presented itself as a defender of Islam, not the conservative Saudi version which underpins the monarchy, but a revolutionary interpretation of the faith opposed to Western colonialism, Israel and monarchical rule.

President Hassan Rouhani, a relative moderate, has said the Saudis are colluding with the U.S. to dominate the region. Iran's Supreme Leader, Ayatollah Ali Khamenei, called the Saudi-led airstrikes "genocide" and compared them to Israel's strikes on Gaza during last summer's war with the Palestinian Hamas militant group.

The Saudi-Iranian struggle is playing out across the region. Lebanon has been without a president for nearly a year, as the Iranian-allied Hezbollah and the Saudi-backed Sunni bloc repeatedly fail to reach a compromise.

Kuwait's parliament voted overwhelmingly to join the airstrikes in Yemen, while nine lawmakers -- all Shiite -- voted against, saying the intervention violated the constitution's requirement that the country only engage in defensive wars.

Kuwaiti lawmaker Faisal al-Duwaisan, who voted for military action, said in remarks carried in local papers that "the war is not against Kuwait's Shiites," but that the government should "protect national unity from the treason of Shiites and their insult."

In Bahrain, where Saudi Arabia sent troops to help the Sunni monarchy quell a 2011 uprising by the tiny island's Shiite majority, at least three people have been arrested for criticizing the Yemen airstrikes.

Among those detained is prominent activist Nabeel Rajab, who wrote on Twitter that war only leads to more bloodshed and hatred, and who shared photos of a burnt corpse and a child buried under rubble. He's being investigated for illegally disseminating footage and information related to Bahrain's participation in the airstrikes.

Immediately after the first airstrikes were launched in the early hours of Mar. 26, Saudi Arabia's highest religious authority sanctioned the military operation as a war to defend religion. The Council of Senior Religious Scholars issued a fatwa, or edict, declaring that any soldier killed in the fighting is a "martyr."

"One of the greatest ways to draw closer to God almighty is to defend the sanctity of religion and Muslims," the council's fatwa said.

Saudi Sheikh Naser al-Omar went one step further, telling his 1.65 million Twitter followers that "it is the responsibility of every Muslim to take part in the Islamic world's battle to defeat the Safawis and their sins, and to prevent their corruption on earth."

In a video posted on his Twitter account Tuesday, he tells dozens of Saudi men seated in a mosque that their "brothers" in Iraq, Syria, Yemen and Afghanistan are fighting a jihad, or holy war, against the "Safawis."

"No one can logically imagine that in this battle with the enemies of God, one can't find a place or role to play," he said. "You may not have the ability in direct killing, but... you can help with financial support or with words online."