Yemen's Houthis have claimed to have seized Perim Island at the mouth of the Bab al-Mandab Strait, a critical international shipping route, according to a source from Yemen's internationally-recognised government. The Iran-backed group also captured the strategic port city of Mokha from Saudi-backed pro-government forces, according to military sources. A Yemeni military official told AFP that the Houthis now control the entire coastline.

The Saudi energy ministry announced on Friday that its east-west oil pipeline was closed as a 'precautionary measure' after it was 'subjected to multiple attacks' in the Riyadh and Medina regions. The ministry reported that the attacks resulted in several injuries. The pipeline, which has been increasingly used to transport oil bypassing the Strait of Hormuz, is now a key concern for Saudi Arabia's energy security.

Saudi Crown Prince Mohammed bin Salman has pressed US President Donald Trump to take military action against the Houthis, according to two sources familiar with the matter. Trump has declined direct US military involvement, offering instead to assist with intelligence and targeting support. A senior Trump administration official told the BBC that the US is in continuous dialogue with Saudi Arabia and the Republic of Yemen government regarding regional stability.

On Friday, Yemeni pro-government forces withdrew from Perim, also known as Mayyun. Witnesses and news agencies reported that Houthi forces moved on to the island. The Houthis issued a statement claiming their military operation to expel Saudi-backed forces was a 'success' and that 'maritime navigation is safe for all companies except for Saudi vessels.' Houthi military spokesman Yahya Sarea said the operation was launched on 3 September due to Saudi Arabia's 'blatant aggression' against 'our dear people.' Sarea also claimed the Houthis had expelled 'Saudi enemy' forces from six districts in the Taiz and Hodeidah regions, with hundreds of troops killed, wounded, or captured. However, the Houthi statement did not mention Perim Island.

Saudi Arabia has not publicly commented on the latest developments. Perim Island sits at the narrowest point of the Bab al-Mandab Strait, which has become increasingly important following the effective closure of the Strait of Hormuz in the US-Iran conflict. Saudi Arabia has been relying on the Red Sea and the Bab al-Mandab Strait for shipping oil to Asian customers. The escalation of the conflict has contributed to a surge in oil prices.

Since the Houthis launched an offensive in the south-west a week ago, hundreds have reportedly been killed and thousands displaced in Yemen. A Saudi-led coalition has carried out air strikes on Houthi-controlled areas in western Yemen, while the Houthis have launched missiles and drones at cities and oil facilities in southern Saudi Arabia. The International Organization for Migration (IOM) reported that at least 46,000 people have been displaced in Yemen since fighting escalated. On Friday, the IOM said the number was 'alarmingly rising by the hour.' Amy Pope, IOM director general, said: 'Families are being forced to flee for the second or third time in this conflict, with almost nothing left.'

The Houthis ousted the internationally-recognised government in 2015, triggering Saudi military intervention in the civil war. The group currently controls much of Yemen, including the capital Sanaa. A truce that had largely held for over four years effectively collapsed in July. What remains unknown is the full extent of the Houthis' control over the Bab al-Mandab Strait and the precise impact of their advances on international shipping and regional stability.