FRANKFURT, Germany (AP) — The capture of the Red Sea port of Mokha and a strategic island by Iran-backed Houthi rebels in Yemen brings their forces to the heart of a key choke point for the global economy: the Bab el-Mandeb Strait leading out of the Red Sea.

The Houthis took Mokha on Thursday and on Friday captured Mayun, also known as Perim, off Yemen’s coast, two officials said, in a swift advance that extends their reach near one of the world’s key commercial lanes.

The strait had been a vital route for crude oil supplies from Saudi Arabia to Asia after shipping through the Strait of Hormuz was restricted due to threat of Iranian attack — until Houthi targeting of Saudi tankers largely ended that safety valve.

The Houthi advance is focusing renewed attention on the Bab el-Mandeb Strait and further risks to shipping there, despite efforts by the Houthis to reassure shipowners that vessels other than those covered by their embargo on Saudi-linked shipping remain safe.

Bab el-Mandeb had served a key workaround for Saudi oil exports