On Tuesday morning, hours after leaving the Lausanne talks on Iran's nuclear programme, Russian Foreign Minister Serge Lavrov was heading back to Switzerland amid growing anticipation that a partial agreement would be announced. The news could not be more unwelcome in Riyadh. As Lavrov was announcing that a deal was probably imminent, though no one could “be a 100 per cent sure”, Saudi Arabia's Foreign Minister Saoud Al-Faisal was insisting that the Saudi-led military intervention in Yemen, which both Russia and Iran had demanded end immediately, would continue until the Iranian-backed Houthis are stopped in their tracks. The stage was set for a diplomatic spat between Moscow and Riyadh. Al-Faisal had already attacked Russian policy in the Middle East during the Arab Summit which ended on Sunday in Sharm El-Sheikh. Moscow, he said, is not only supporting the destabilisation of Yemen but is also condoning the continued killing of Syrian civilians at the hands of forces loyal to Bashar Al-Assad. “The Saudis are extremely uncomfortable about the deal being hammered out in Lausanne. They want to make it clear that they refuse to be demoted to a second regional power and will not condone any expansion of Iranian influence in what they still view as their exclusive zone of influence,” says a Cairo-based European diplomat. Yemen, other diplomats concur, is seen in Riyadh as “an annex” to the oil-rich kingdom. When the Arab Spring hit Yemen in 2011 the Saudis were quick to engineer the removal of Yemeni President Ali Abdullah Saleh and his replacement by a successor who had bowed to Riyadh's will. Today, say diplomats, Riyadh is lobbying Washington, and the ten members of the coalition it forged to intervene militarily in Yemen, to begin ground operations against the Iranian backed Houthis, ahead of imposing a political deal that will deny Tehran any say in Yemen's future. “Whatever happens in Switzerland, Riyadh wants to make it clear that Tehran will not be allowed to challenge Saudi influence, and certainly not in its backyard, Yemen,” says an Egyptian diplomat. Most informed diplomats agree that the real battle being fought is between the Sunni oil rich kingdom whose word is law in most Arab and many Muslim capitals — “several of those who joined the coalition in Yemen would not have done so had it not been demanded by the Saudis, and this includes some GCC members,” says a North African diplomat — and oil rich Shia Iran. “The Sunni-Shia battle is real. That was made clear by the immediate positioning made by Hizbullah leader Hassan Nasrallah who in a fiery speech soon after the start of operations in Yemen criticised Saudi Arabia for intervening in Yemen and applauded Iran for not intervening though of course we all know that there are Iranian military personnel in Yemen,” says an Egyptian diplomat. Nasrallah's speech, he points out, elicited a retort from Lebanese politician Saad Al-Hariri defending Riyadh's actions and highlighting the Sunni-Shia fault lines that define the conflict. “It was clear what the Saudis were up to from the beginning. They wanted a Sunni coalition so they called on the Turks and other key Sunni Arab states to join and they refused to take no for an answer,” says the Egyptian diplomat. Riyadh, he adds, is already making its displeasure felt in Arab capitals have not been as forthcoming as the Saudis expected. Talk of a regional Sunni-Shia tug of war is hardly new. It first surfaced a decade ago when Jordan's King Abdullah and former Egyptian President Hosni Mubarak warned of Tehran's ambitions to win greater influence in Arab countries that have sizeable Shia minorities or, in the case of Sunni-ruled Bahrain, Riyadh's closest GCC ally, a Shia majority. During Israel's war on Lebanon in 2006 Riyadh openly encouraged the elimination of the Shia Islamic resistance movement Hizbullah, egged on by many of its Arab allies. Middle East based Western diplomats argue that the Shia-Sunni feud is only a part of what is happening. “It is also a power struggle between two traditional regimes fighting over influence not just in their immediate neighbourhood but in north, and even sub-Saharan, Africa,” says a Cairo-based European diplomat. Few people expect the Iranian-Saudi battle over power to end soon. In Iraq, one theatre for the ongoing conflict, Riyadh scored an unexpected success when, with US support, Iraqi Prime Minister Nouri Al-Maliki, who enjoyed Tehran's backing, was replaced. In Syria the Saudis, under a new monarch less antagonised by Assad than his predecessor, still support radical militant groups fighting the Syrian regime. “They are doing this despite their own apprehension over the threat posed by the growing regional presence of such groups, not least to the Gulf monarchies. For now the overriding concern is Iran,” says a Riyadh-based foreign diplomat. The expected deal with Iran, he adds, will inevitably force a regional reshuffle of power and the Saudis and Iranians are now marking out what they see as their zones of influence. In press statements on the fringe of a Kuwaiti hosted meeting to coordinate humanitarian aid for Syrian refugees, the Saudi foreign minister said Iran's re-integration in the region remains dependent on its political choices. “Iran should seek cooperation and not to export its revolution,” said Al-Faisal. Al-Faisal's statements were made as Riyadh was preparing for a high-level meeting that aims to produce a political roadmap for Yemen. Few expect that the dispensation the Saudis want to see will include a role for its opponents in Yemen. The Houthis are now allied with former Yemeni president Saleh. Once firmly in the Saudi camp, Riyadh will be unwilling to condone any political role Saleh whose new political associations have placed him beyond the pale. But then nor is Riyadh in a position to reinstall Saleh's successor Abd Rabu Hadi, who lacks popular support. They will most probably opt for a figure such as Ali Nasser Mohamed, a Yemeni from the south who pulls considerable political weight. The Saudis are hoping that whatever deal they come up with will send a clear message to Tehran, and other international powers, that the fate of the region cannot be decided away from the house of Al-Saud. Following meetings on the fringe of last week's Arab summit with senior Egyptian and Saudi officials former Arab League Secretary General Amr Moussa told the press that neither Washington nor Tehran should presume they are in a position to reorder the Arab Middle East without the support of Arab countries.