In short:
Smoke and flames have been seen near Riyadh's international airport as Yemen's Houthis claim to have attacked "sensitive" sites in the Saudi capital.
uncertain
Houthis → see → capital
Saudi Arabia had sent alerts warning of potential danger around Riyadh but has not yet confirmed the Houthis' claims.
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Arabia → send → claims
The Iran-backed Houthis have been launching attacks against Saudi cities, energy infrastructure and shipping, creating new threats to global oil supplies.
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Houthis → back → supplies
Yemen's Houthis say they have attacked "sensitive" sites in the Saudi capital Riyadh with missiles and drones, hours after flames and a large plume of smoke were seen near the city's main airport.
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flames → say → airport
Saudi Arabia had sent alerts on Saturday, local time, warning of potential danger around Riyadh, amid an escalation in Houthi attacks in the kingdom.
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Arabia → send → kingdom
Reuters video and photographs showed a huge pillar of black smoke rising in the area, with the airport highway, main terminal building and other facilities in the foreground.
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pillar → show → foreground
At one point in the video, flames were visible rising from behind what appeared to be fuel tanks.
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what → rise → video
The Houthis did not specify what they had targeted in Riyadh, but said they had also attacked an Aramco facility in the Red Sea city of Yanbu, a key Saudi oil export hub.
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they → specify → Yanbu
The Houthis said the operation came in response to an attack in the Yemeni capital Sanaa.
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operation → say → capital
Saudi civil defence sent the alerts by phone overnight for potential danger of aerial attacks in Riyadh and the city of Al-Kharj east of the capital, before issuing an all-clear on Saturday morning.
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defence → send → morning
A Reuters journalist in Riyadh's Olaya area heard booms before the all-clear was sent.
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clear → hear → booms
Although some alerts had been issued in Riyadh this year after the start of the US-Iran war, these were the first since the escalation began with the Houthis in July.
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escalation → issue → July
Houthi warning
The Houthis, who control the most populous parts of Yemen and much of the north, have been launching attacks against Saudi Arabia since declaring a naval blockade against Riyadh in July, with strikes targeting Saudi vessels in the Red Sea.
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who → control → Sea
The attacks have targeted Saudi cities, energy infrastructure and shipping, creating new threats to global oil supplies and putting at risk the main alternative Red Sea route for Gulf exports, while traffic through the Strait of Hormuz remains blockaded.
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traffic → target → Hormuz
On Friday, Houthi military spokesperson Yahya Saree said the group had foiled unspecified "criminal attempts" in the Yemeni capital Sanaa, blaming Saudi Arabia and vowing a response.
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group → say → response
The Iran-aligned group, which seized Yemen's entire Red Sea coast in a lightning advance this month, says the Saudi Air Force has conducted hundreds of air strikes against it in recent days.
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Force → align → days
The fighting between the Houthis and Saudi Arabia has developed as a new theatre of conflict in the wider war that began with US and Israeli strikes against Iran at the end of February.
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that → develop → February
Mohsen Rezaei, secretary of Iran's Supreme National Security Council, told Al Jazeera in an interview aired on Saturday that Tehran wanted the war between Saudi Arabia and the Houthis to end, adding that he believed Yemenis also wanted a settlement with Saudi Arabia.
Mr Rezaei also said Iran had conveyed its conditions to mediators for re-engaging in stalled negotiations with the United States, including "ending the war on all fronts".
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Iran → tell → fronts
Consultations were continuing with Qatari and Pakistani mediators and Tehran was awaiting a response from US President Donald Trump, Mr Rezaei said.
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Rezaei → continue → Trump
The UN Security Council in a statement on Friday "condemned in the strongest terms continued Houthi attacks against the Kingdom of Saudi Arabia, including attacks impacting civilian and energy infrastructure, which have resulted in the injury of civilians, including women and children".
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which → condemn → women
In the statement, the Security Council also condemned "Houthi military escalation in Yemen".
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Council → condemn → Yemen
The Aporia
