US air strikes targeting Yemen’s capital have killed 12 people and injured 34 others, the Houthi rebels said early on Monday.The deaths mark the latest in America’s intensified campaign of attacks targeting the rebels.

The US military has quietly racked up a major toll in Yemen, killing at least 500 Houthi fighters—including top-tier operatives—since last month, according to officials and sources familiar with intelligence assessments.

Yemen's Houthi rebels say the U.S. military has launched a series of airstrikes on the capital, Sanaa, and a rebel-held coastal city.