install.packages('maps')

iso = maps::iso3166

> str(iso)
'data.frame':   269 obs. of  5 variables:
 $ a2         : chr  "AW" ...
 $ a3         : chr  "ABW" ...
 $ ISOname    : chr  "Aruba" ..
 $ mapname    : chr  "Aruba" ...
 $ sovereignty: chr  "Netherlands" ...