Arab leaders gather in Saudi Arabia on Thursday for emergency summits that Riyadh hopes will deliver a strong message to Iran that regional powers will defend their interests against any threat following attacks on Gulf oil assets this month.
Saudi and the United Arab Emirates, which have lobbied Washington to contain their foe Iran, have said they want to avoid war after drone strikes on oil pumping stations in the kingdom and the sabotage of oil tankers off the UAE coast.
Riyadh accused Tehran of ordering the drone strikes, which were claimed by Yemen's Iran-aligned Houthi group. A top U.S. security official said Iranian mines were "almost certainly" used in the tanker operation. Tehran denies any involvement.
Saudi Foreign Minister Ibrahim al-Assaf told a gathering of his counterparts in Jeddah ahead of the summits that the attacks must be addressed with "strength and firmness".
"While summit leaders are likely to discuss how best to avoid a war, King Salman is equally determined to defend Saudi and Arab interests amid increasing tensions between the U.S. and Iran," Prince Turki al-Faisal, former Saudi intelligence chief and envoy, wrote in an opinion piece published by Al Arabiya.
He said the meetings of Sunni Muslim Gulf leaders and Arab leaders at midnight in Mecca would discuss Shi'ite Iran's "interference" in Arab affairs.
Tensions have risen between the United States and Iran after Washington quit a multinational nuclear deal with Iran, re-imposed sanctions and boosted its military presence in the Gulf.
U.S. National Security Advisor John Bolton said on Wednesday that the attack near a UAE bunkering hub was connected to the strike on pumping stations on the kingdom's East-West pipeline -- both alternative oil shipping routes to the Strait of Hormuz -- and a rocket attack on Baghdad's Green Zone.
"There is no doubt in anybody's mind in Washington who is responsible for this and I think it's important that the leadership in Iran know that we know," Bolton said of the operation against four vessels, including two Saudi oil tankers.
He said the United States was trying to take a "prudent and responsible" approach but warned Tehran against any new attacks.
An Iranian official dismissed Bolton's remarks as "a ludicrous claim". The Islamic Republic has said it would defend itself against any military or economic aggression.
During the U.S. adviser's visit to Abu Dhabi, officials activated a defence cooperation agreement signed earlier this year between the United States and the UAE, which hosts a U.S. air base.
Gulf states have a joint defence force under the Gulf Cooperation Council (GCC), but the 39-year-old alliance has been fractured by a dispute that has seen Saudi Arabia, the UAE, Bahrain and non-GCC Egypt impose a political and economic boycott on Qatar since mid-2017.
Saudi King Salman invited Qatar's ruler, whose country is home to the largest U.S. military base in the region, to the Mecca summits. Qatar said Prime Minister Sheikh Abdullah bin Nasser Al Thani would attend, the highest level Qatari official to visit the kingdom since the rift.
Iraq and Oman, which have good ties with Tehran and Washington, have said they are working to reduce tensions. Doha, which shares a giant gas field with Iran, has offered to help.
Iranian Foreign Minister Mohammad Javad Zarif said on a trip to Iraq this month that Tehran wanted balanced ties with Gulf neighbours and had proposed signing a non-aggression pact with them.
One of the UAE's main newspapers said in an editorial, which are usually state-approved, that the offer was "bizarre".
"No Mr Zarif. We are not buying your 'nice neighbour' routine," said the front-page editorial in Gulf News daily.