If the GTVA suspected the UEF to try to communicate with the Shivans, then they'd have no reason to keep that secret. It's a better justification for the war than all the current official reasons combined.
Everyone in the GTVA fears the Shivans a great deal and the argument that they are trying to stop the UEF from making a terrible mistake that would destroy them and possibly take the GTVA down with them, would ring very well with the Shivan-paranoid GTVA population. Support for the invasion would be massive.
And if that really was the reason behind the war, they'd never have fought with the gloves on in the first place (or whatever you want to call Severantis way). The Shivans are far too dangerous to care about collateral damage.
Now if the GTVA only got aware of the secret project right before they put Steele in charge, that would make more sense, because that would explain why suddenly keeping collateral damage to a minimum is no longer important.
But I don't think even that would work for a simple reason: Vasudans.
If the GTVA thought the UEF was going to contact the Shivans, the Vasudans wouldn't sit by and watch.
It doesn't just have to be the Shivans you know, Nagari allows for communication with Vishnans too. Khonsu is reluctant to put anything in Sol as he wants to keep the Vasudan military ready for what he believes is the real threat.
I'm convinced at least that the GTVA went to war for more than just the public reasons and it may or may not have something to do with Byrne's project, which itself may or may not be something similar to ETAK (though I believe it is). It's entirely possible that on a very high level both sides are aware of what the other is doing to some extent and that they have very different opinions on whether or not this is dangerous to the species' continued survival. The Terran assembly may well fear that if the Vasudans find out the full story they may take the side of the UEF. The Vasudans may in fact already know, distrust between the two races may mean they are both withholding vital information from one another.
According to the fiction, Vasudan members of the security council were never consulted before the invasion of Sol and the council may have known about Byrne's project before the 14th went in. The GTVA *thinks* that this project poses a threat to them, which would justify an invasion, but it may not necessarily pose a threat to the human race, at least not yet. If it did they would have charged in with their full armada to put a stop to it.
It could be a case that the longer the project remains in development the greater the threat it poses. There may be a threshold where its development simply can't be stopped, like Iran's nuclear ambitions.
I don't want to rely too much on techroom entries, but reading through them there are a lot of simliarities in the way the Council of Elders and Khonsu's administration work: they both combine hard science with metaphysics and mysticism and they both have members who claim they speak to alien minds. The 'great apocalyspe' which Khonsu is preparing his race to fight may be the same cause the UEF is preparing for and for whatever reason the Terran assembly doesn't agree.
Or it's all bull****.
