I am wondering what the Bible says concerning going to war for unjustified reasons? What if a country deceives its people and claims reasons for going to war, but there is evidence that does not justify war? How do Christians and Christians in the military handle this type of situation?
A government's authority, whether they recognize it or not, is derived from God. "Let every soul be subject to the governing authorities. For there is no authority except from God, and the authorities that exist are appointed by God" (Romans 13:1). When a government makes decisions that are contrary to God's teachings, Christians are required to obey the higher authority. When the apostles were told not to teach, "But Peter and John answered and said to them, "Whether it is right in the sight of God to listen to you more than to God, you judge. For we cannot but speak the things which we have seen and heard"" (Acts 4:19-20). And on another occasion, "But Peter and the other apostles answered and said: "We ought to obey God rather than men"" (Acts 5:29).
This means that no Christian can give blind obedience to rulers. It is for a similar reason that at the end of World War II members of Germany's army were tried for war crimes. The world in general recognized that Hitler's orders were morally wrong and so the soldiers were held responsible for not making morality a higher standard.
It should be remembered that disagreeing with a government placed in authority is not a light matter. Just because you disagree is not enough because you are not God. It cannot be a matter of personal opinion. It has to be established by what God has said that what is being demanded by a rogue government is wrong.