For some reason I have been under the impression that the AI in SR2020 doesn't conduct amphibious invasions.
I started a new game on the laptop, as South Africa. My goal is to unite the African continent.
India and several other countries have declared war on me. I've ignored them, however. But I began to receive messages that I've lost control of some areas of my territory due to lack of supply. I continued playing, trading on the world market, conducting diplomacy, doing research.
I scrolled around and discovered that I had lost a substantial piece of territory in the southeast. Indian units were there and were advancing inland. A group of Indian warships and transport ships had traveled around to the other side of South Africa and were off my west coast.
I easily dealt with the ground forces that had landed and the naval forces that were off my coast.
But I was impressed! Now I'm maintaining strong air patrols over the Indian Ocean to guard against a repeat invasion.