At a meeting held in Saudi Arabia's capital Riyadh on Saturday with ministers from the kingdom as well as its allies Bahrain, Kuwait, Qatar, Oman and the United Arab Emirates, Kerry told reporters the relationship between the US and those nations was built on "mutual interest."

"The United States will stand with them against any external threat and defend if necessary together with them against those threats," Kerry (pictured left) said at a press conference held alongside Saudi Foreign Minister Adel al-Jubair.

For his part, al-Jubair said he did not see a coming together of the United States and Iran following the nuclear deal and lifting of sanctions.

"Overall I think the United States is very aware of the danger of Iran's mischief and nefarious activities... I don't believe the United States is under any illusion as to what type of government Iran is," he said.

Rivals Saudi Arabia and Iran accuse one another of stirring up instability in the Middle East. They support opposing sides in the wars in Yemen and Syria. Tensions worsened this month when Sunni-ruled Saudi Arabia executed a top well-known Shiite Muslim cleric, triggering an attack on Riyadh's embassy in Tehran by Iranian protesters and the severing of diplomatic ties.

Syria talks

During his Riyadh visit Kerry also sought agreement on which groups opposing Syrian President Bashar al-Assad should be represented at imminent international peace talks aimed at bringing Syria's almost five years of war to an end. The dispute over the opposition negotiating team as well as demands by opposition forces for Russia to halt bombing and the Syrian government to lift sieges may stall the negotiations.

Kerry said he was confident the talks, set for January 25, would go ahead next week. He was also due to hold talks with Saudi King Salman, the deputy crown prince and the chief negotiator for the Saudi-backed Syrian opposition, Riyad Hijab.

According to Reuters, Syrian armed rebel groups said Saturday that they held the Syrian government and Russia responsible if peace talks failed, even before negotiations were due to start in Geneva.

"We hold the Assad regime and its Russian ally responsible for any failure of the political process due to their continued war crimes," a joint statement from dozens of rebel factions cited by Reuters said.

se/rc (Reuters, AP, AFP, dpa)