Manama (AFP) - French Defence Minister Florence Parly took aim 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 increased with attacks against tankers, a US unmanned drone being downed, and strikes on key Saudi oil facilities.

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.

"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 key 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.