In watching CCTV-4 news, I frequently see country names abbreviated but miss the leading character before I can look it up carefully (I know the major ones). Is there a list anywhere of those standard abbreviations (most of the form X国)?
I think this is a fairly exhaustive list of currently existing countries. This does not encompass unabbreviated country names that end with 国 (e.g., 孟加拉国):
Most countries can be abbreviated by the first character in their name especially when describing the relations between two or more countries. There are some exceptions and many will be duplicates.
So you can put two countries together + 战争 War, + 冲突 Conflict, + 关系 Relations, etc.
We only refer to some countries this way:
德国 (Deutsch)，法国 (France)，美国 (America), 英国 (England), 俄国 (Russia) - these countries were the first countries to visit China. Maybe at that time people began to learn English and translated the name in a different way.
Also 俄国 is more for referring to Russia before Soviet Union (苏联). Current Russia we call 俄罗斯.
For 韩国 (south Korea), it's because Koreans call their country 大韓民國.
For 泰国, I'm not sure.
For other countries' names, we try to use the pronunciation for translation: