Saudi Arabia says it has evidence showing Iran sponsored Saturday's drone and missile attacks on two of its oil facilities, and called on the international community to take action. The question is whether there could be a war.
The scale of the attacks means that Saudi Arabia cannot overlook what happened, and its decision to identify Iran as the culprit compels the kingdom to respond.
The Saudis will probably wait until a team of independent experts from the United Nations has completed an investigation into the incident.
Although the experts are likely to come to the same conclusions - namely, that the attacks could not have been carried out without Iranian material support and guidance - the process will give the Saudis time to consider their options.
For Iran, deniability is not going to help.
Saudi Arabia and its allies believe the country has raised the stakes in order to convince US President Donald Trump to ease the crippling economic sanctions he reinstated when he abandoned a nuclear deal with Iran last year and demanded a new one be negotiated.
Iran's leaders hope that the risk of the region sliding into war will bring world powers to the realisation that the sanctions are a recipe for disaster.
They had been hoping that a plan by French President Emmanuel Macron to offer a $15bn line of credit to Iran, in return for its compliance with the nuclear deal and a halt to its destabilising activities in the region, would come to fruition. But the plan has not been approved by Mr Trump.
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