Sovereign nation-state is just a synonym of a country. It's an entity that has control over a certain area with its own ability to govern its people. Invading other nations is a direct violation of that right to govern their own people.
If a country choose to invite another nation, that country might have to face the risk of punishment from international organizations such as the United Nations. They can either be embargoed by the members or even directly intervened by the soldiers from the United Nations.
The distinction drawn between the marital as well as the non marital children would then be under the Equal Protection Clause. The court will put immediately a scrutiny standard and would implement the action unless it is substantially related to a vital government interest
