From: Near Portland, OR
Today Japan and China are buying large amounts of US coal from Wyoming because it is much cleaner and better quality than what is available in Asia. Just after the earthquake in Japan I started seeing massive trains loaded with coal headed west. The BNSF mainline through the Columbia Gorge passes right through my town.
As far as being prepared, what really changed in the 20th century was what the attacked did in wars. In the 19th century and before, most wars were of limited scope and the attacker would punch their neighbor hard, then the neighbor would sue for peace. It happened in the 1870 Franco-Prussian War, the Spanish-American War, the Mexican-American War, and the last was probably the war between Japan and Russia in 1906. But there are many other wars that fit this pattern of relatively short spats that were resolved by some territories switching hands.
In the early parts of WW II, WW I was mostly seen as an anomaly. It was thought that mobile warfare would result in more quickie wars. The Germans had some early victories that made it look like that was the pattern for the 1940s too. They did take out Poland, Norway, Denmark, and the Western European countries in short order. They got stopped at Britain, but then they didn't really have the naval assets to take on a defended island nation with a big navy.
Japan was bogged down in China, but every time they wanted to take more territory, they didn't have much trouble doing so. In the early going in the SRA and elsewhere it looked like it was going to be a short war. They were taking on an empire that was already conquered (the Netherlands), another that was already stretched to the max (the UK) and one that most of the world thought was a second rate military (the US).
The derision the Axis powered had towards the US is laughable today, but it was very real in 1941. I recently read something about what the German top people were saying to one another about the US in 1941. Hitler laughed at Roosevelt's aircraft production quotas, even though his quotas to date had been met. The idea the US could be producing 100,000 planes a year by 1944 was considered the punchline to a joke. Herman Goering remarked that the only thing Americans could build were refrigerators.
Many of Japan's top military people thought that the large influence women had in the US made Americans weak. If they smacked the US hard enough, they figured the US with their heavy female influence would run away. Yamamoto knew better, he had traveled around the US and knew it better than any other top leader in Japan. He is famous for his prediction that he would run loose in the Pacific for six months, then from then on it would be a mater of trying to hold onto the gains.
Yet another factor we can't get today is that democracy was not universally seen as one of the most stable forms of government as it is today. Democracy was a fairly rare form of government in the 1940s. Outside of the Commonwealth, US, and western Europe, it was almost unknown.
The Axis powers pretty much considered democracies fatally flawed forms of government that could be brought down if the country was hit hard enough. The UK changed governments the day Hitler invaded France. Though the UK ended up with a far stronger PM than the one who fell. It was a close run thing. Parliament almost picked a pro-Nazi to be PM instead of Churchill.
20/20 hindsight going to war with the west is seen as insane. In the mindset of Axis leaders in 1939-1941, it's not as crazy a prospect as it looks now.
On Dec 6, 1941 the US was deeply divided about getting into the war with the isolationists out numbering those who wanted to fight. Pearl Harbor was the first time anybody saw how a democracy with a divided public responded to a foreign attack on one of their biggest naval bases. As it turns out, it served to instantly turn a huge number of isolationists into war-hawks. Before it happened, it was hard for the Japanese to know for sure what would happen.
There are rumors Roosevelt knew about Pearl Harbor and let it happen. I'm not convinced of that, but he knew his country much better than the Japanese did and he could predict more accurately what would likely happen if the US was attacked. If he did know and kept quiet about it, it was a good bet on his part how public opinion would shift.
WitP AE - Test team lead, programmer