The UK will be involved, and on this occasion in a dispute that is legal. Many lives will be lost, but many more will be saved from murder and torture at the hands of the incumbent Government. It is hoped the pressure will break the loyalty of government forces quickly and encourage the Gaddafis to flee.
We cannot know that. We cannot predict how many casulties will be suffered in the process of destroying Libyan armour and air defences. We do not know whether the Opposition will come to be dominated by liberal democrats or militant zealots. War is a conversation in the language of unintended consequences.
It is though a moment of hope, for millions of Libyans in their darkest hour, as the drone of engines close in on their last redoubts in Benghazi and Misratah.
This is still their civil war to win. The international community has not offered to disarm mercenaries in Tripoli. But at least they will fight in the shade of our warbirds.
All our hopes for a swift resolution are with the brave men and women who are to provide that cover, fight on the ground, and negotiate peace when the outcome is clear. The long overdue global collapse of authoritarianism inched a little closer today.