(Reuters) -Iranian-backed Houthi militants in Yemen have stepped up attacks on vessels in the Red Sea, impacting a shipping route vital to East-West trade. In response, some shipping companies have instructed vessels to instead sail around southern Africa, a slower and therefore more expensive route. The U.S. and Britain launched dozens of air strikes against Houthi military targets overnight on Jan. 11 and 12 in retaliation for the attacks, widening regional conflict stemming from Israel’s war in Gaza. Below are actions taken by companies (in alphabetical order): C.H. ROBINSON The global logi…