Isolationism is akin to "good fences make good neighbors." This doesn't
mean we don't trade or take care of growing problems that could actually
affect us. However, what has happened is that we don't stay in our
yard, don't keep our fence mended, go into other peoples' yard all the
way over on the other side of town and "tell 'em how it's gonna be from
now on", etc. etc. Of course, this comes from our new job in Globotown
where we are one of the globocops. We use to be globo-farmer/educator/
inventor/etc. Under our burden of national debt and negative consumer
savings, we are also now globo-debtor. In such a position we can't be
isolationist because we are
no longer independent.
Their actual point was that the US was moving against the Japanese well before the attack on Pearl Harbor.
Whether or not we were "moving against" them, we had a significant
presence in the Pacific. Recall that we were already in the Philippines
before the start of the last century and had been involved in China as
well. Japan could not expand without running into us. Ironically, it was
earlier contact with the US that had shown the Japanese where the
world was going. Like they've shown before, the Japanese took an
outside idea and ran with it to its logical conclusion.
Had we stayed in our yard the world we be a very different place and
maybe not for the better. The Axis may have still been defeated because
of their small populations and the amount of land the USSR and China had
available from which to operate. Or, we might now be dealing with a fascist
Eurasian empire --as friend or foe? Who knows.