This puzzle is part of the Monthly Topic Challenge #1: Restricted Title: xkcd 1xxx
Below, you will see a map with twenty UN members or observer states labelled with one or more letters from A-G (except one, which is labelled 'X'). Additionally, seven images of basketballs are presented, numbered 1-7.
TASK: Deduce the map labelling rule that enables you to pair up each letter A-G with exactly one number 1-7. Additionally, explain with justification which letter(s) should take the place of the black 'X' near the centre of the map.
(Click image to enlarge)
For avoidance of doubt, the labelled countries on this map are (in alphabetical order): Democratic Republic of the Congo, Estonia, eSwatini, Ethiopia, Guinea-Bissau, Liechtenstein, Netherlands, North Korea, North Macedonia, Palestine, Saint Kitts and Nevis, Saint Vincent and the Grenadines, São Tomé and Príncipe, South Korea, South Sudan, Switzerland, Turkmenistan, United Arab Emirates, United States, and Uzbekistan.