The South African rand plunged on Thursday after the US accused the country of arming Russia.The currency dropped more than 30 cents against the dollar in minutes, reaching its lowest level since the historic slump in 2020, local media reported.The US ambassador to South Africa Reuben Brigety claimed that South Africa had supplied weapons and ammunition to a Russian ship that visited the Simon's Town naval base in Cape Town in December last year.The allegation sparked concerns that the US would impose economic sanctions on South Africa.President Cyril Ramaphosa's office said a retired judge would lead an independent investigation into the matter.