Saudi Arabia has joined an international maritime mission to protect commercial shipping in the Strait of Hormuz and other areas.
Saudi state media reported the move on Wednesday, citing an official source in the defence ministry.
The mission is already joined by Australia, Bahrain and the United Kingdom.
The US formed the coalition after attacks on oil tankers that American officials blame on Iran, as well as Iran's seizure of tankers in the region.
The attacks have rocked world commodities trading, but Iran denies being behind the explosions.
The operation area for the International Maritime Security Construct covers the Strait of Hormuz, Bab al-Mandab, the Sea of Oman and the Arabian Gulf, the Saudi state media report said.
Australian Associated Press