The Saudi-led Arab coalition said it detected indications of an imminent danger to navigation and global trade south of the Red Sea, Saudi state media reported early on Monday.
The coalition said also that it detected hostile movements and activity by the Iran-backed Houthi militias using explosive laden boats.
Measures are being taken to neutralize the threat and ensure freedom of navigation, it stressed.
Earlier this month, the coalition announced that it had destroyed a vessel the Houthis had booby-trapped to use in an imminent attack, in violation of the Stockholm Agreement in place in the Hodeidah province.