The US military says it has launched strikes on the Iranian-backed Houthi group in Yemen, striking 15 targets.
The Pentagon said it used aircrafts and warships to launch the attacks in order “to protect freedom of navigation”.
Several explosions were reported in some of Yemen’s main cities, including the capital Sanaa.
Since November, the Houthis have launched attacks on around 100 ships in the Red Sea, sinking two vessels in the global conduit for $1tn (£760bn) in trade. The rebel group says the attacks are retaliation for Israel’s military campaign in Gaza.
Central Command, which oversees US military operations in the Middle East, said the attacks targeted weapons systems, bases and other equipment belonging to the Houthis.
Houthi-aligned media say the Yemeni capital of Sanaa was among cities hit.
On Monday, the Houthis said they had shot down a US-made MQ-9 Reaper drone over Yemen. The US military acknowledged losing an unmanned aircraft.
Last week the Pentagon said the Houthis had launched “a complex attack” on US Navy ships in the region, though all of the weapons launched were shot down.
Sanaa has had a respite from bombing in the past two years since fighting between the warring parties in Yemen largely subsided.
As well as the attacks on ships in the Red Sea, the Houthis have fired several missiles and drones at Israel directly.
In July a drone launched from Yemen struck Tel Aviv, killing one person and injuring 10. Last month, the group fired several missiles at Israel, including one that targeted Israel’s main airport.
Both times Israel responded by attacking sites in Yemen.
Earlier this year, the US, UK and 12 other nations launched Operation Prosperity Guardian to protect Red Sea shipping lanes against the Houthis.
The Houthis are part of a network of armed groups in the Middle East backed by Iran that includes Hezbollah in Lebanon and Hamas in Gaza.