Javier PÃ rez de CuÃ llar Guerra ( born January 19 , 1920 in Lima ) is a Peruvian diplomat who was the fifth Secretary-General of the United Nations from January 1 1982 to December 31 1991 . Javier PÃ rez de CuÃ llar y de la Guerra ( born January 19 , 1920 ) is a Peruvian diplomat who served as the fifth Secretary-General of the United Nations from January 1 , 1982 to December 31 , 1991 .