Defiant rebel leader Abdulmalik al-Huthi slammed the intervention as “unjustified”, calling in a televised address for supporters to confront the “criminal oppressive aggression”.
President Abedrabbo Mansour Hadi arrived in Riyadh, with officials saying he was on his way to Egypt to take part in a two-day Arab League summit starting on Saturday.
It was the first confirmation of Hadi’s whereabouts since the rebels began advancing this week the main southern city of Aden, where the president had been holed up since fleeing the rebel-controlled capital Sanaa last month.
Their advance raised Saudi fears the Shiite minority rebels would seize control of the whole of its Sunni-majority neighbour and take it into the orbit of Shiite Iran.
Saudi Arabia launched the air strikes before dawn Thursday, saying it had assembled a coalition of more than 10 countries, including five Gulf monarchies.
The Saudi ambassador to the United States, Adel al-Jubeir, said the coalition stood ready to do “whatever it takes” to protect Hadi’s government.
On the eve of the regional summit in Egypt, Arab League chief Nabil al-Arabi also declared full support for the strikes following a “coup”.
But Iran reacted with fury, condemning the intervention as “a dangerous step” that violated “international responsibilities and national sovereignty”.
President Hassan Rouhani said it amounted to “military aggression” and “condemned all military intervention in the internal affairs of independent nations”.
After hitting targets overnight in Sanaa and elsewhere, the coalition launched fresh strikes late Thursday, hitting a rebel-held base in third city Taez and the airport and an arms depot in the Huthis’ northern stronghold, officials and witnesses said.
Powerful explosions had been heard earlier in Sanaa as warplanes pounded an air base adjacent to the international airport and other locations, an AFP correspondent reported.
Sanaa families streamed out of the capital seeking the relative safety of the provinces.
“I am leaving with my family — Sanaa is no longer safe,” said one resident, who gave his name only as Mohammed, as he piled his belongings into a minibus.
In the south, residents reported hearing explosions at the huge Al-Anad air base, north of Aden, which was seized by anti-government forces on Wednesday.
Saudi-owned Al-Arabiya television said the kingdom had deployed 100 fighter jets to the operation, while the United Arab Emirates had committed 30, Kuwait 15 each and Qatar 10. Bahrain said it had committed 12 fighters.
The channel said Saudi Arabia had also mobilised 150,000 troops near the border, while all civilian flights were halted at seven Saudi airports in the border region.
The government in Riyadh said it was boosting security on its borders and across the kingdom, including at the OPEC kingpin’s crucial oil facilities.
Washington said President Barack Obama had authorised the “provision of logistical and intelligence support” for the campaign.
US officials told AFP Washington was looking at providing refuelling and early warning radar aircraft to Saudi Arabia in support of the operation.
A Saudi adviser said the strikes had taken out Huthi air defences and destroyed “numerous Huthi fighter planes,” adding that the air force “has pretty much secured most of the Yemeni air space”.
Egypt, Jordan, Sudan and Morocco confirmed they were joining the campaign.
Egypt, whose government announced it was prepared to commit ground troops, said its air force and Navy were taking part in response to “demands by the Yemeni nation for the return of stability and to preserve its Arab identity”.
But like Iran, Shiite-majority Iraq said it opposed the Saudi intervention, with Foreign Minister Ibrahim al-Jaafari calling for a peaceful settlement, as Lebanon’s Shiite movement Hezbollah accused Riyadh of “aggression” in Yemen.
US Secretary of State John Kerry held a conference call with Gulf ministers to discuss the operation and “commended the work of the coalition taking military action against the Huthis,” a senior US official said.
‘No impact’ on nuclear talks
The Saudi adviser said his country’s defence minister warned the son of ousted Yemeni president Ali Abdullah Saleh, “who is commanding the attack on Aden that his forces face ‘obliteration’ if they continue their push” on the city.
Saleh, who resigned in 2012 following a year of nationwide protests, is accused of allying with the rebels, relying on the loyalty of many army units that he built during his three-decade rule.
Dozens of people have been killed as the Huthis backed by troops allied Saleh have clashed with pro-Hadi forces in their drive southwards.
Yemen has been gripped by growing turmoil since the Huthis launched a power takeover in Sanaa in February.
The Saudi-led intervention triggered a sharp rise in world oil prices on fears the conflict could threaten supplies.
Washington insisted the intervention would have “no impact” on nuclear talks with Tehran, as last-ditch efforts to reach a deal before a March 31 deadline were launched in the Swiss city of Lausanne.
“We have always been clear that the P5+1 negotiations are solely focused on the nuclear issue,” a senior US official told AFP, requesting anonymity and referring to the group of six nations engaged in talks. – AFP