I found this sentence interesting -- I've been under the impression for some time that preemptive war is not necessarily a traditional doctrine, at least in America, and was introduced in the post-9/11 national security backlash era. But I don't know enough about military history to really know.
What was controversial in the Bush Administration was an attempt to expand the concept of preemptive war to include what is also referred to as "preventive war", where the attack is not "imminent" as that concept had been traditionally understood, but a more distant presumed eventuality. This had been traditionally (and generally remains, despite the efforts made by that administration) viewed as a subtype of aggressive war.
("Traditionally", here, means particularly in the post-WWII, under-the-UN-Charter, world in which states are viewed to operate under a regime of international law in which resort to force, except in immediate self-defense -- possibly collective -- or as directly authorized by the Security Council is forbidden. Though this generally follows other theories of war and its legitimate justification that make similar distinctions, such as Catholic Just War doctrine.)
Japan's attack on Pearl Harbor was a preemptive move in their eyes.
Imagine how Americans would feel if Russia established a huge military base halfway between Russia and America in the middle of the ocean somewhere. Now imagine that nuclear weapons don't exist.
In that scenario, a preemptive strike might start to make sense to a lot of people in America.
That's pretty much how Japan felt about Hawaii before Pearl Harbor.
I'm not justifying Japan's attack. It was a horrible tragedy. But it's totally understandable, if not laudable.
If not for the threat of nuclear war, I'm sure we would have attacked Cuba. It very nearly happened anyway.
(Of course, without the existence of nuclear weapons, the USSR never would have even attempted that move in the first place)
I'm not certain what exactly 'preemptive war' is supposed to be, either than war undertaken in order to preempt a worse possibility (which would seem to be the traditional doctrine for going to war in general).
America's first war, the Quasi-War with France, could be seen as a kind of pre-emptive war in order to prevent further seizures of our ships, which was seen as worse than the war itself.
The First Barbary War was waged in order to prevent the Barbary Pirates (of Tunis, Tripoli & Algiers) from seizing & enslaving our merchant sailors. It should stand to reason that war was considered preferable to continued enslavement of American citizens.
The War of 1812, of course, was waged in response to certain British provocations whose continuation was considered worse than war.
The Second Barbary War was again waged in order to prevent the Barbary Pirates from seizing & enslaving our sailors.
Past 100 years is exception as rifles, machine guns, mines and then antitank missiles have made defense lot easier than assault. If it's lot more effective to dig in and wait, the rhetoric loses credibility. I'm oversimplifying of course.