The United States has hit more than 800 targets in Yemen since mid-March, killing hundreds of Houthi rebel fighters, including members of the group's leadership, the US military said Sunday. Washington's forces have hammered the Houthis with near-daily air strikes since March 15 in an operation dubbed 'Rough Rider,' seeking to end the threat they pose to vessels in the Red Sea and Gulf of Aden and reestablish US regional 'deterrence.'