SANAA, Yemen: A multinational coalition, led by Saudi Arabia, that has been fighting Houthi rebels in Yemen said Monday that the firing of a ballistic missile at the kingdom's capital, Riyadh, could constitute "an act of war" by Iran, which it blamed for the attack.
The Saudi-led coalition also said it would "temporarily" close all of Yemen's ports of entry in response to the missile firing.
It was the second major episode over the weekend in which Iran was accused of trying to destabilise the region, after Prime Minister Saad Hariri of Lebanon said Saturday that he was quitting his post, largely because of what he said was interference from Tehran.
"Iran's role and its direct command of its Houthi proxy in this matter constitutes a clear act of aggression that targets neighbouring countries, and threatens peace and security in the region and globally," the Saudi-led group said in a statement. "The coalition's command considers this a blatant act of military aggression by the Iranian regime, and could rise to be considered as an act of war against the kingdom of Saudi Arabia."
Iranian Foreign Minister Mohammad Javad Zarif said on Monday Saudi Arabia was blaming Iran for the consequences of its own "wars of aggression", after his Saudi counterpart accused Tehran of threatening regional security.
"KSA (Saudi Arabia) is engaged in wars of aggression, regional bullying, destabilising behaviour (and) risky provocations. It blames Iran for the consequences," Zarif said on his Twitter account.
Riyadh, which is widely believed to have orchestrated Hariri's departure - while also carrying out a sweeping transformation of its own governance that saw 11 prominent figures arrested over the weekend - left open the possibility that this would not be its final word on the matter.
"The coalition command also affirms that the kingdom reserves its right to respond to Iran in the appropriate time and manner," it said in a statement.
With Iran, which is largely Shiite, and Saudi Arabia, which is mostly Sunni, each trying to assert dominance over the Middle East, Yemen has emerged as a battleground.
With the support of Iran, the Houthis overthrew the internationally recognised government of President Abed Rabbo Mansour Hadi in early 2015, and they have controlled much of the country since. The fighting has led to an immense humanitarian crisis - the United Nations has described it as the world's worst - in which 10,000 people have died and at least 3 million have been displaced.
The latest step in the conflict came Saturday, when a ballistic missile fired from Yemen came close to Riyadh before being intercepted by the Saudi military. Yemen's Houthi-controlled Defence Ministry said its forces had targeted Riyadh's airport with a long-range missile.
Immediately after the firing, the Saudi-led coalition hit the Yemeni capital, Sanaa, with the heaviest barrage of airstrikes in more than a year.
While the Houthis have long had loose ties to Iran and have received some support, there has never been proof that they were proxies under the "direct command" of Tehran, as the Saudis assert, analysts say.
It is unclear whether Tehran has sent, or even could send, missiles to Yemen, which is under a tightly controlled air and sea blockade. In recent years, ships believed to be from Iran have been intercepted transporting small weapons, but there have been no reports involving missiles or missile parts.
The top commander of the Islamic Revolutionary Guards Corps in Iran denied that his country had provided the rebels in Yemen with missiles, describing the accusation as "baseless."
"It is not possible for the Islamic Republic to transfer missiles to Yemen," the commander, Maj. Gen. Mohammad Ali Jafari, told the semi-official news agency Tasnim. "These missiles were produced by the Yemenis and their military industry."
The Houthis' emerging use of ballistic missiles nevertheless suggests there is some merit to allegations from Saudi Arabia, the United States and Israel that Iran is providing parts or technology. Analysts at IHS Jane's say that it would be difficult for Iran to ship whole missiles to Yemen, but that the missiles could have been acquired from North Korea before the current conflict started.
Saudi Arabia has set up a sea blockade around Yemen, assisted by others, including the U.S. Navy. The kingdom has also bought hundreds of billions of dollars of advanced weapons and bombs from the United States and Britain.
Brig Gen Hossein Dehghan, an adviser to Iran's supreme leader, Ayatollah Ali Khamenei, rejected the notion that his country was involved in the attack on Riyadh. "The people of Yemen are defending themselves," he said.
He also pointed to Saudi Arabia's deals with Washington and London for arms being used in Yemen. "Today, we should ask Saudi Arabia under what pretext it has been attacking Yemen with all its equipment from air, land and sea," he said.
On Sunday, in addition to shutting down Yemen's points of entry, the Saudi-led coalition announced bounties for 40 members of the Houthi leadership, ranging from $20 million to $40 million each, describing the targets as "terrorists." Most of the people on the list were members of the government that had been formed with the party of the ousted former president, Ali Abdullah Saleh.
Riyadh has been attacked twice before with missiles from Yemen, in February and March. The Saudi border area, including military bases in the southern city of Jizan, has also been targeted several times.
Separately, state television in Iran reported that Tehran and Riyadh had been unable to work out an arrangement that would allow Iranians to travel to Saudi Arabia for umrah, a minor pilgrimage that can be made at any time of the year. The major hajj pilgrimage, in contrast, is defined by specific dates on the Islamic lunar calendar.
There was no indication that the failure to reach an accord was linked to the developments in Lebanon and Yemen.
The Iranian news agency ISNA quoted Hamid Mohammadi, who leads the Hajj and Pilgrimage Organisation in Tehran, as saying that Iran and Saudi Arabia would hold talks in December for hajj travel next year.
No Iranians are thought to have travelled to the holy Saudi city of Mecca for the hajj in 2016 because of tensions between the two countries. A year earlier, thousands of pilgrims, including 464 Iranians, died in a stampede there, prompting Iranian leaders to accuse the Saudis of mismanaging the holy sites. An agreement was later reached to allow Iranians to travel to Mecca this year.