When considering how to take over Europe, young Adolph certainly wouldn't be planning a blitzkrieg in 2006. Nope, he would have learned from today's non-military incursions and then organized Germans to be guest workers who would immigrate themselves into France, England and other desired targets of Nazi lebensraum. So much cheaper than building thousands of tanks and planes.
It also helps when the political class of the country to be invaded cares more about cheap labor for its corporate masters than protecting national sovereignty.
Immigration is an effective form of asymmetric warfare now being used by Muslims against Europe and by Mexicans against the United States. It accomplishes the final goals of military conquest — settling new lands, acquiring access to more natural resources, expanding a group's cultural influence — without all the messy warfare.
Alien invasion. At least some are calling it by the right name now.