The equation of the latest war in the Middle East began with countless unknowns surrounding Iran that needed to be clarified: its ability to withstand bombing, which turned out to be greater than expected; its ability to rebuild its military arsenal, which also exceeded forecasts; as well as its ability to close the Strait of Hormuz - something it has practically maintained since the beginning of the confrontation, writes Ignacio Farisa for the newspaper "Pais".
Today, after the agreement reached, the biggest question marks are related to this narrow sea passage - only 34 kilometers at its narrowest point, but through which 1/5 of the oil and liquefied natural gas (LNG) consumed in the world passes. Will ships be able to pass freely again from Friday onwards, or will they have to pay some kind of fee? Will shipping companies and, more importantly, insurers believe it? And does Tehran really, as it has already hinted, reserve the right to close the strait again if the situation worsens in the coming months?
The promise - one of many - of the President of the United States is that the strait will return to normal operation "immediately".
"It will be open to everyone", Donald Trump announced on Saturday.
"Ships of the world, start your engines! Let the oil flow!", he added a day later, when the agreement was already a fact, although Iran continued to remain officially silent on the matter.
Waiting for this to really happen - this time definitively - are more than five hundred vessels of all types: from bulk carriers to container ships, from oil tankers to gas carriers. They have been stranded in the area for more than three months and should soon be heading back to the Indian Ocean.
This would be a relief for the thousands of sailors on board, some of whom are working in almost inhuman conditions. Finally, good news after 105 days of ordeal. The end - or so it seems - of their odyssey.
If the Republican president's words prove true, the change will be enormous compared to the current situation. Although the double blockade of the Strait of Hormuz had become significantly more permeable in recent weeks, with dozens of crossings per day, ships that dared to cross the strait had only three options: reach an agreement with the Iranian Revolutionary Guard, be escorted by the US Navy, or turn off their transponders to avoid detection and risk their lives.
Their hope - it remains to be seen whether it will be justified - is that after Friday they will no longer have to perform such acrobatics to pass through the strait.
On the threshold of summer
The theoretical opening of the Strait of Hormuz comes at a critical moment.
If the strait were to enter the summer season with a "closed" sign, the risks to the global economy would increase exponentially. Stocks of oil, natural gas and their derivatives - gasoline, diesel, kerosene, fertilizers - are already alarmingly low, especially in Southeast Asia and the United States.
Europe was approaching the peak period of jet fuel consumption with huge doubts about whether it would be able to supply airlines. Moreover, if problems were to be avoided in the winter, now was the time to fill gas storage facilities. With the world's third-largest LNG exporter, Qatar, virtually out of the game, the task seemed daunting.
That's no longer the case.
If oil and gas tankers could once again move freely from Qatar, the United Arab Emirates, Saudi Arabia, Iraq, Kuwait and Bahrain to Ningbo-Joushan in China, Vadinar in India, Rotterdam, Zeebrugge, Montoire-de-Bretagne or Algeciras, the latest peak in tensions would quickly be a thing of the past.
That would mean a return to square one - and an end to fears of a second major energy crisis this decade, following the one triggered by the pandemic's exit and the Russian invasion of Ukraine.
It would also bring new revenue to the Gulf states, whose economies were already showing signs of tension.
The price of Brent crude, the main European oil benchmark, is currently around $80 a barrel, well below the nearly $120 level reached in late April.
This is a significant relief that is likely to increase in the coming months. At the beginning of the year, when Trump's threats against Iran still seemed a distant prospect, crude oil was around $60 a barrel and supply was more than ample.
If the Strait of Hormuz is finally opened, there is no reason why these levels cannot return in the medium term - as soon as the dwindling strategic reserves are restored.
Damage and distrust
The last big question is related to the state of the energy infrastructure in the Persian Gulf countries.
Some of it suffered billions of dollars in damage during the war. Dozens of facilities, including the world's largest gas field - South Pars, located between Qatar and Iran - were bombed.
Some of them have already resumed normal operation. Others have not yet done so.
A full assessment of the damage is yet to be done and it remains to be seen how quickly energy extraction and transportation can be restored.
Despite the many unknowns, financial markets have been cheering for days on progress toward a possible agreement that would allow global energy supply chains to normalize.
They were severely disrupted by Russia’s invasion of Ukraine in 2022, and the joint offensive by the United States and Israel against Iran has plunged them into even more dangerous uncertainty.
If all goes according to plan, that uncertainty could begin to ease as early as Friday.
However, it will take weeks, if not months, for maritime traffic in the area to fully recover. Only time will restore confidence in this strategically important region.