I recall a novel I read back in the 80s about an scientific survey ship from Earth being destroyed in orbit around an alien planet. When the messages from the ship arrive on Earth years later, a military expedition is organized to return to the alien world and force them to surrender.
Most of the international expeditionary force is composed of younger kids (12-13 years old) who will be woken from stasis years before arriving at the target and trained as soldiers. The action in the book picks up mainly during this training phase, as the invasion fleet is nearing the alien planet and follows several characters including a young female recruit, an Israeli tanker and others.
When they arrive at the target planet they find that the alien civilization there is not what they expected and does not seem to have the technology to attack an interstellar spacecraft. Despite this, the expeditionary force invades the planet, beginning a grueling and bloody war that nearly results in the extermination of the alien species.
After the climatic battle in which the aliens are finally defeated, another invasion force from Earth arrives in orbit. They had departed Earth a couple of decades after the first force had left and thus have more advanced weaponry and faster ships. They leaders of the newly arrived fleet reveal that the government back home had been able to better discover what had happened to the survey ship given more time to analyze the available data.
It turns out that the survey ship had been destroyed by an alien ship from an entirely different planet and that the planet that has been invaded (and its civilization destroyed) had nothing whatsoever to do with the attack on the Earth ship and that the war had happened only because they were defending themselves from an "alien" (from Earth) invasion force.
I remember that the human military forces were part of an organization denoted by the acronym S.C.A.F but I do not recall if they ever said what that stood for (I don't think they did actually.)
I also remember some kind of commentary about how the Israeli contingent couldn't function without ample supplies of Coca-Cola, and that one of the main characters is killed by a land mine in the final scene.
Please help, thanks.