Saudi Arabia has few options amid mounting threats from Iran, its allies

A lightning advance by Houthi rebels threatens a crucial Red Sea shipping route.

Drone attacks blamed on Iraqi militias have forced the closure of a major pipeline, and Iran is still disrupting the Strait of Hormuz.

It's a nightmare scenario for Saudi Arabia, and it has sent jitters through global markets.

The Saudis' most essential ally, the United States, has been unpredictable and sometimes unreliable.

US President Donald Trump seems reluctant to widen an already unpopular and stalemated Mideast war ahead of congressional elections.

For Iran, the rebels' advance and closure of the pipeline ramp up global economic pressure as its grip over the Strait of Hormuz has been loosened.

Michael Ratney, a former US ambassador to Saudi Arabia, said the latest developments are "incredibly frustrating" for the kingdom.

"Despite their antipathy for the Iranians, this is a war they had never asked for, they had great trepidation about.

And once it started, all of their worst-case scenarios .