The United States has been unable to prevent Yemen's Houthi rebel forces, backed by Iran, from disrupting global shipping in the Red Sea. The attacks have forced commercial shipping companies to circumnavigate Africa, increasing shipping costs and cutting traffic through the Suez Canal in half. The US and UK launched Operation Prosperity Guardian to intercept Houthi attacks, but the operation has failed to secure Red Sea shipping lanes. The flexibility and low cost of the Houthi operations, which use drones and missiles estimated to cost between $2,000 and $50,000, have made deterring the threat costly for the US.