Gulf Arab states will hold a summit this week to discuss a controversial proposal to form an EU-like union at a time of regional turmoil and fresh Iranian overtures.
Saudi Arabia and other oil-rich monarchies, already rattled by the turmoil unleashed by the 2011 Arab Spring, fear a landmark nuclear agreement reached last month could herald a wider rapprochement between the West and their regional rival Iran.
But a proposal to develop the Gulf Cooperation Council into a fully-fledged union has proven divisive, with Oman threatening to leave the GCC if the idea is approved. The group also includes Saudi Arabia, Kuwait, Qatar, Bahrain and the United Arab Emirates.
"The summit is held amid extremely sensitive and delicate situations that require member states to study the consequences for the GCC," Secretary General Abdullatif al-Zayani said ahead of the two-day summit, which opens Tuesday in Kuwait.
The summit comes a week after Iranian Foreign Minister Mohammad Javad Zarif visited four GCC states to reassure them over the interim nuclear agreement, which would freeze some of Iran's nuclear activities in exchange for some sanctions relief.
Relations with Iran "are entering a new space different from the past. A space that is extremely positive and constructive," Kuwait's foreign ministry undersecretary Khaled al-Jarallah told reporters after Zarif's visit.
But Zarif did not visit the most important GCC member, Saudi Arabia, although he said he plans to do so in the future.
"Iran is trying to exploit the momentum generated from the nuclear deal and Saudi Arabia is trying to repulse this push," Saudi political analyst Khaled al-Dakhil told AFP.
"Tehran is trying to create a wedge between Saudi Arabia and some GCC states like Oman and Qatar."
Saudi Arabia, which cautiously welcomed the nuclear deal, is engaged in an increasingly sectarian proxy war with Iran in Syria, where Riyadh backs the Sunni-led rebels and Tehran is a key ally of President Bashar al-Assad's embattled regime.
Kuwaiti Foreign Minister Sheikh Sabah Khaled Al-Sabah, whose country is hosting the summit, told reporters on Friday that the conflict in Syria will be high on the agenda.
The Gulf leaders are also expected to discuss Egypt, where Saudi Arabia, the UAE and Kuwait strongly backed the July 3 military overthrow of Islamist president Mohamed Morsi, whose government was seen as close to Qatar.
The conservative Gulf states -- which sit on 40 percent of global proven oil reserves and a quarter of the world's natural gas -- largely dodged the pro-democracy protests that erupted nearly three years ago.
The one exception was Bahrain, where the Sunni monarchy launched a fierce crackdown on protests led by the Shiite majority, with Saudi Arabia leading a military intervention to back the regime.
As the Arab Spring gathered pace Saudi Arabia in 2011 proposed creating a Gulf union, though it never spelled out what that would entail.
Bahrain was an early supporter of the idea, while other members expressed reservations.
Kuwait and Qatar have since come around to the proposal, while the UAE has not yet adopted a firm position.
But Foreign Minister Yusuf bin Alawi of Oman -- which enjoys closer ties to Iran -- on Saturday expressed opposition to the idea.
"We will not prevent a union, but if it happens we will not be part of it... we will simply withdraw" from the new body, he said.
Efforts to deepen economic ties -- through the creation of a customs union and a common currency -- have meanwhile stalled, even as the gross domestic product of thee six states has risen five-fold over the past decade to $1.6 trillion.
Analysts have said the Gulf monarchies' best hope for survival lies not in strengthening their alliance but in embracing region-wide calls for reform.
"There has been a clear rise in the pace of demands for reform in the GCC states despite the security crackdown," said Anwar al-Rasheed, chairman of the Gulf Forum for Civil Societies, a liberal pan-Gulf group.
"Change is inevitable, and the only option for Gulf ruling families is to transform peacefully into constitutional monarchies."