We remember that
Hitler started WWII by invading Poland
in 1939. We figure that if we forbid the
invasion of neighboring countries, we can prevent WWIII. And we don’t like invasions on humanitarian
grounds; the people in the invaded country take it in the neck. Ask any Pole, they will tell you.
Ever since WWII America has believed that national borders
should be inviolate. We have even fought
wars over this, the Korean War being the clearest example. North Korea
invaded South Korea
with out warning. We raised a huge army,
fought a vicious 3 year war, and preserved the original state of South
Korea.
As a side effect, today’s South Koreans have a warm spot in their hearts
for Americans. They have industrialized
and are now an important power. They
were nowheresville back when the Korean War started.
One other factor in the Ukraine situation. Today’s Russia is smaller; less populated, and has fewer natural resources than the old Soviet Union had it its disposal. We would just as soon keep things that way. The old Soviet Union was a dangerous competitor. When the Soviet Union broke up in 1989, about a third of it became independent of Russia. The new Russia, although a powerful state, is not as powerful as the old Soviet Union was.