Arab states in the Persian Gulf have greeted the interim nuclear deal struck between Iran and the West in Geneva with sullen silence.

Despite their muted response, however, the Gulf states have watched the growing signs of reconciliation between the US and Iran with undisguised horror. As the Geneva talks rolled into Saturday night and a deal edged closer, Saudi Arabia's King Abdullah summoned the emirs of Kuwait and Qatar to Riyadh for talks on how to respond.

The world's largest oil producer and a staunch American ally for decades, Saudi Arabia has led the Arab world's diplomatic push for the US to crush the Iranian nuclear program. In a US diplomatic cable published by WikiLeaks in 2010, Abdullah was quoted as urging Washington to "cut off the head of the snake", in reference to Iran.

To the Gulf Arabs, a deal between Iran and the West threatens the balance of power in the region. If Iran is welcomed back into the international fold, its potential as a hub for business, trade and tourism, buoyed by huge untapped reserves of oil and gas, is enormous.

In the end, the three Gulf monarchs gathered in Riyadh said nothing. Saudi officials said they could not publicly criticise the Geneva deal, but that deep concerns remained about Iran's wider ambitions in the region, particularly in Syria, where Iran has sent troops to support Syrian President Bashar al-Assad while Saudi Arabia and Qatar have funnelled weapons and cash to the rebels.

"The concern is that by agreeing to curb its nuclear program Iran will get a free pass elsewhere in the region, particularly in Syria," said one Saudi official, who spoke on the condition of anonymity.

Most troubling for the Gulf states is the sense that their influence in Washington is waning. A former Saudi ambassador to the US, Prince Bandar bin Sultan al-Saud, was installed as the kingdom's intelligence chief last year to capitalise on the influence he wielded during the two Bush presidencies. But he has found the Obama administration very different and more cautious, than its Republican predecessors.

"There is real fear that America is shedding all its responsibilities in the region, that our diplomacy has failed. We need to seek new alliances elsewhere," said the Saudi official.

However, the US remains the dominant military power in the region and its support is essential to Arab security.

Despite misgivings, the United Arab Emirates welcomed the Iranian nuclear deal as "a positive step".

"This deal has a narrow focus in the sea of problems we have with Iran. Syria remains a huge concern," said Abdulkhaleq Abdulla, a prominent UAE political commentator whose positions often reflect those of the government. "But overall the deal is a relief. Anything that reduces tensions between the US and Iran is positive for the region."

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