Cuba's missions in 68 countries are manned by 25,000 Cuban doctors. Medical teams have worked in crisis such as the South Asian tsunami and the 2005 Kashmir earthquake. Nearly 2,000 Cuban doctors are currently working in Africa in countries including South Africa, Gambia, Guinea Bissau and Mali. Since the Chernobyl nuclear plant exploded in 1986, more than 20,000 children from Ukraine, Belarus and Russia have traveled to Cuba for treatment of radiation sickness and psychologically based problems associated with the radiation disaster. In response to the 2005 Hurricane Katrina disaster, Castro offered to send a "brigade" of 1,500 doctors to the U.S. to provide humanitarian aid, but the U.S. never accepted.