Marines from Outer Space. No, Really.
Somewhere in the Great Beyond, Robert Heinlein is smiling. The U.S. Marines want to make his Starship Troopers a reality within the coming decades.
Rapid-response Marines could be delivered anywhere on the globe within a couple of hours, inserted from a space station via small craft designed to carry 13 warriors each. Since national air space ends 50 miles above the earth, they could pass over multiple international boundaries without needing to seek permission. (Remember, Turkey turned down the U.S. request to move troops through it during the Second Gulf War, and that had significant impact on what happened in post-invasion Iraq.) Of course, diplomatic issues could still be raised by the country to which they’re inserted. (Think Pakistan today.)
In a way, this is reminiscent of the challenges the Marine Corps confronted between the world wars. Traditionally, landing parties had been sent ashore at port cities, using small boats sent out from bigger ships. New amphibious invasion techniques developed by Holland "Howlin’ Mad" Smith and others during the peacetime years made possible the landings in the Pacific, Normandy (Yes, the Army adopted those techniques, too.) and elsewhere.
As with the Space Marine concept – apologies to Games Workshop; the U.S. Marine program is officially called the Small Unit Space Transport and Insertion program – 20th-century attempts at creating new ways to insert amphibious troops required challenging existing doctrine and finding the technology to make new methods possible, such as Higgins boats and Amtracs.
Is the concept daunting? Oh, yeah. Is it possible? Moon landings, computers small enough to use at home, and portable telephones that take pictures were all considered science fiction within my lifetime.
And never, ever, underestimate what a few determined Marines can accomplish.