There was no such thing as an 'international police force'. The only way to stop the Nazis was to go to war against Germany. The peoples of the Western democracies weren't very keen on this ...
a couple of countries weren't expected the invasions like: Poland but Germany were all ready to invade any country at war. the allies allowed Germany to invade Poland.
Invade other countries.
yes, he did many countries in the 1940s
he really invaded Poland Hungary and other neighboring places but he did not invade the USA
France that's one
Austria
With his army
No, because by that time Hitler had lost the war, and committed suicide.
He invaded the country called spell properly
Hitler, Austrian by birth, had no reason to invade Germany. About two years after becoming chancellor of Germany, Hitler had a firm choke hold on the entire country, so he then focused on invading other countries.
Hitler also invaded Poland along with many other countries! Hitler didn't invade Germany. The Nazis invaded Poland, France, and the USSR. This is after they annexed Austria and the Sudetenland of then Czechoslovakia.
Hitler did not invade North Korea.