After the Aramco attack, Saudi Arabia retaliated against the capital of Yemen, at the military bases of the Yemeni rebels.

According to residents and rebel-controlled Al-Masirah TV, all raids on Sana'a were directed at Houthi rebel sites and military camps near the city's airport. A separate blow also struck them, in the port province of Hodeidah.

Back on Friday, the Houthis bombed the Saudi Aramco oil refinery in Riyadh. According to media reports, the attack resulted in a fire that was subsequently eliminated without any damage to the supply of oil or derivatives. No casualties were reported.

Of course, this escalation could hinder US efforts to end the seven-year war in Yemen, which has led to the world's worst humanitarian crisis - widespread hunger and disease.

The conflict is also compounded by the confrontation between the US and Iran over how to revive the 2015 agreement aimed at containing the Islamic Republic's nuclear program.

In 2015, the Saudi-led coalition joined the conflict in Yemen to try to rebuild its internationally recognized government.

Houthi attacks on Saudi Arabia rarely caused any damage or loss of life. But the frequency of the attacks has increased dramatically lately, arousing concern in the Persian Gulf, a region that is key to world oil production and transit. According to the Saudi Arabian authorities, several attacks on Riyadh have been stopped.

With regards to oil prices, after collapsing below $ 68, it became stable and traded around $ 60.