Mike, you've strayed into the absurd here.
How can you argue that Just War theory permits killing when in the same way a lie would avoid killing? If a president could have told a single lie (or even a series of lies) to avoid a war that would kill thousands, that would be a "just" war?
There is a "just war" concept in scripture, and that concept indicates that tactical deception of the enemy in combat is perfectly moral.
In Exodus 2, the Hebrew midwives deceive the Egyptians about their saving of Hebrew boy babies. We are explicitly told that God blessed the midwives for this.
In Exodus 3, God explicitely instructs Moses to deceive the king of Egypt--God gives Moses the deception word-for-word.
In Joshua 2, Rahab deceives soldiers of Jericho to protect the Israelite spies. James explicitly praises her for her deception.
In 1 Samuel 21, David feins insanity to protect himself from the King of Gath's revenge.
In 2 Kings 6, when Elisha’s prayer blinded the enemy army, after which the prophet deceived them into following him into captivity.
In 2 Chronicles 18 and 1 Kings 22, God sends a "lying spirit" to deceive King Ahab, who has made himself God's enemy.
In John 7, when Jesus' brother suggested He go to the Festival of Tabernacles to display Himself for public recognition (the second temptation that Satan attempted in the wilderness), Jesus told them He would not. Yet, He did...and in disguise at that.
All of these are examples of tactical deception in warfare (either physical war or spiritual war). None of these examples is criticized in scripture, some of them are explicitly praised...and a couple are practiced by the LORD Himself.
When you look at the scriptural requirements to speak the truth, each of them specifically characterize circumstances in which we are bound to speak the truth. Those circumstances all involve cases in which we are bound to the other person(s) by a covenant of some kind. Facing the enemy in combat is not one of those circumstances.
It is a soldier’s moral duty to his commander and fellow soldiers to deceive his enemy and not to betray those whose trust is in him. God fully recognizes this.