Short-term rates for container shipping between Asia, Europe and the United States are climbing on reduced capacity caused by the threats to cargo vessels in the Red Sea.

The rate spike is the result of vessels taking the longer route round the Cape of Good Hope to avoid missile strikes from Yemen’s Iran-backed Houthi militants.

The spot rate for shipping goods in a 40-foot container from Asia to northern Europe now tops $4,000, a 173% jump since mid-December, Freightos.com, a cargo booking and payment platform, said late Wednesday.

Yemen’s Houthi rebels are causing one of the most serious disruptions to global trade since the pandemic began with attacks on merchant ships crossing the Red Sea on their way to the Suez Canal. At least 18 shipping lines, including Swedish giant Maersk, have rerouted routes through South Africa to avoid passing through the strategic Gulf of Aden .