US forces have struck more than 1,000 targets in President Donald Trump’s campaign against Houthi militants in Yemen, the Pentagon said, offering rare insight into a stepped-up offensive that’s been conducted largely in secret.

American forces have hit more than 1,000 Houthi targets in Yemen as part of a campaign that began in March to stop attacks by the militants on the shipping lanes of the Red Sea, the Pentagon said Tuesday.

The United States intensified strikes on Yemen's Iran-backed Houthis this year to stop attacks on Red Sea shipping, but rights activists have raised concerns over civilian casualties.