French Defence Minister Florence Parly took aim on Saturday at “gradual US disengagement” in the Middle East and said its failure to respond to provocations blamed on Iran set off a dangerous chain of events.

Since May, tensions in the Gulf have escalated alarmingly with attacks against tankers, a US unmanned drone being downed, and strikes on key Saudi oil facilities in September.

Iran was blamed but denied involvement.

Despite the attacks on its Saudi ally and having one of its own drones shot down, the United States has avoided equivalent retaliation.

“We've seen a deliberate gradual US disengagement,” Parly said at the annual Manama Dialogue on regional security, adding it had been “on the cards for a while” but had become clearer with recent events.

“When the mining of ships went unanswered, the drone got shot. When that in turn went unanswered, major oil facilities were bombed. Where does it stop? Where are the stabilisers?” she asked.

“The region is accustomed to the ebb and flow of US involvement. But this time it seemed more serious.”

Parly said the US drawback was a “slow process” and acknowledged that a US carrier strike group had just entered the Gulf.

“But the trend is, I think, quite clear and thus probably irrespective of who wins the next elections.”

The US aircraft carrier strike group Abraham Lincoln sailed through the Strait of Hormuz last week to show Washington's “commitment” to freedom of navigation, the Pentagon said.

It was the first time a US aircraft carrier group has passed through the strait since Iran downed a US drone in June in the same area.

Speaking from the same stage in Bahrain, Saudi Minister of State for Foreign Affairs Adel al-Jubeir insisted there was no US withdrawal from the region and no doubt about its commitment.

“We believe the US is very dependable ally, and has been for the past seven decades,” he said of its staunch ally.

“There is a desire in the US historically to try to retreat from the international scene, but that desire is not reflected in America's posture.”

Jubeir defended Riyadh's measured response to the September strikes, saying the kingdom was being “strategically very patient” in its investigation so there is “not a shadow of doubt” on where the drones and missiles came from.

“We have said all along we don't want war, so to jump into war very quickly is not a rational position.”

Red lines

The French defence minister also put herself at odds with the US on maritime security in the Gulf, after Washington earlier this month launched a maritime coalition based in Bahrain to protect shipping in the strategic Strait of Hormuz.

France instead favours a European mission which Parly said should be able to start “very soon”.

“We want to make clear that our policy is separate from the 'maximum pressure' American policy,” she said, referring to Washington's increasing sanctions against Tehran.

“I would like to add that we are not subtracting anything, we are adding, as a number of countries would not have participated in the American initiative anyway.”

In a wide-ranging and strongly-worded speech, Parly also spoke out on the dangers of chemical weapons again being used in Syria — an outcome that would be a red line for France.

“Yes there is a risk and when you look at (rebel-held) Idlib province there is a strong risk,” she said.

“I am convinced that if these weapons were used again that France would be ready to react again.”

She also homed in on strains on Nato, saying it remained the cornerstone of security in Europe but that it was “time to move from the brain-dead to the brainstorm”.

French President Emmanuel Macron stirred controversy this month saying he believed Nato was undergoing “brain death”, lamenting a lack of coordination between Europe and the US, in an interview with The Economist magazine.

Parly said proposals will be laid on the table at the alliance's summit in London in December including for a group of “wise persons or elders to think about the future of Nato”.