"Given that there is a strong possibility that negotiations with Iran may or may not take place in the near future, I will make my decision on whether to go ahead or not within the next two weeks." This was the statement read out by White House spokeswoman Karoline Leavitt at a press conference on Thursday. It took the US president just 48 hours to make up his mind. On Saturday night, the US bombed Iran's three main nuclear sites: Fordo, Natanz and Isfahan. This is a major escalation in the conflict between Iran and Israel. It is also a decision that took everyone by surprise.

At the end of last week, there was a consensus among observers that the two-week deadline was mainly a way for Washington to regain control of the narrative and buy itself some time. This is especially true given that Donald Trump has already used the two-week tactic several times, notably on tariffs and the war in Ukraine. According to a tally by NBC, this deadline has been brandished twelve times in the last two months.

Given that little has usually happened after previous ultimatums, everyone was somewhat skeptical about the direct involvement of the United States. The markets have reacted little since the start of the conflict. Between the start of the Israeli offensive on June 13 and Wall Street's close on Friday, the S&P 500 fell by only 1%. Over this period, safe-haven assets also saw no major movements: the dollar rose slightly, while gold and 10-year US bonds even corrected slightly. Only oil rose sharply. But at $77 a barrel for Brent on Friday evening, the market was not anticipating a major crisis scenario either.

Until now, the markets have continued to bet that Donald Trump will always back down in the end; this is the famous "TACO trade". Perhaps this is the lens through which we should view his weekend decision: the need to restore his own credibility. Because fundamentally, Donald Trump has always denounced the "endless wars" of his predecessors, and his base is opposed to any foreign military intervention. He is therefore taking a huge risk. Both for himself, politically, but also and above all for the entire Middle East.

Everything will now depend on Iran's response. Donald Trump seems to be betting that the destruction of nuclear facilities, which he is demanding, will force Tehran to negotiate the terms of its surrender. But Iran could instead carry out its long-standing threats: strike US bases in the region or destabilize hydrocarbon supplies, either by blocking the Strait of Hormuz or by targeting the infrastructure of Washington's allies in the Gulf.

For now, however, investors' central scenario is somewhat similar to Donald Trump's: US strikes will end the conflict. A severely weakened Iran will have no choice but to seek peace.

At least, that is what can be gleaned from this morning's very measured market reactions. European indices opened slightly lower, while US futures are around break-even. Oil, meanwhile, has already wiped out most of its gains, despite opening higher.