Martin Griffiths is stepping down for health reasons after nearly three years of trying to tackle mounting humanitarian crises in Ukraine, Gaza and Africa. U.N. Secretary-General António Guterres praised Griffiths "for his tremendous leadership and service to the United Nations and the humanitarian community in advocating for people affected by crises and mobilizing resources to address their needs" Griffiths, 72, told The Associated Press earlier this month that he got a severe case of COVID-19 in October and is still