In the months since an attack by Hamas militants on Israel triggered a war in Gaza that has ignited unrest throughout the Middle East, the United States has rushed thousands of US service members to a region that had seen a steadily declining US presence over years.

But many of those new US troops are on warships and aircraft that move in and out of the region, and are only temporarily deployed. That US strategy to rely on surge forces could be tested now Iran and Israel have broken the taboo of open military strikes against each other.

"What it means for the US military is that I think we have to revisit this idea of what are the necessary, sustainable (military) capabilities that we have to maintain in the region," said Joseph Votel, a retired four star Army general who led US troops in the Middle East.

Sustained focus

Votel and other former officials said the US military's success in downing Iran's drones and missiles last Saturday was presumably aided by detailed US intelligence that allowed the Pentagon to anticipate the timing and targets of Iran's attack.

"I think the bigger concern is our ability to be responsive over a sustained period of time," Votel said.

US officials say Iran does not appear to want an all-out war with Israel, and Tehran has played down Friday's strike. Still, experts warn the situation is unpredictable, particularly as long as the Israel-Hamas conflict rages.