The Iranian-backed rebels, who have targeted Israel and shipping in the Red Sea, said children were among those killed in the strikes ordered by President Trump.

The strikes represent the biggest U.S. military operation in the Middle East since Trump took office, and come as the U.S. increases sanctions pressure on Iran while trying to bring it to the negotiating table over its nuclear program.

Oil futures climbed on Monday, finding support after the U.S. over the weekend launched U.S. strikes on Houthi rebels in Yemen, raising the risk of disruptions to oil flow in the region.

Oil traded higher on Monday after the United States vowed to keep attacking Yemen's Houthis until the Iran-aligned group ends its assaults on shipping while Chinese economic data fuelled hopes for higher demand.

Oil prices on the New York exchange are rising in response to data from China and U.S. strikes on Houthi positions, brokers report. Analysts at Goldman Sachs Group Inc. are already lowering their oil forecasts for the Brent benchmark due to numerous unfavorable factors affecting the commodity's prices.