This is a general theme about interactions among sovereign states. For example, the theme may pertain to war, peace, diplomacy, international trade, and globalization.

Examples:
"transnational institution for peace" is an "international issue" theme as it is used when an organization like the UN, a forum for sovereign states to discuss common concerns, is featured.

References:
https://en.wikipedia.org/wiki/State_(polity) https://en.wikipedia.org/wiki/Transnationality https://en.wikipedia.org/wiki/International_relations https://en.wikipedia.org/wiki/Global_issue