Japan, during the latter part of the war, was desperate to bring the hurt to United States soil. It was suffering terribly from the effects of long range bombardment presaged by the largely symbolic Doolittle Raid after Pearl Harbor. Japan did not have a V-2 program, and its atomic research program was crude. It did have strong paper balloons used in stratospheric research. A military man, Major General Sueyoshi Kusaba came up with the idea of using the balloons as a bomb delivery device. By floating a hydrogen filled balloon into the prevailing easterly jet streams at 30,000 feet an attached bomb could reach the western United States in three days. The Japanese floated thousands of balloons, but only about 300 bombs dropped over the western United States. The operation never amounted to more than a nuisance, but incendiaries did start a few forest fires, and a few civilian casualties were inflicted. The US military, for fear of civilian panic, kept the public in the dark about the operation.The Japanese bomb balloons were a primitive example of a non-ballistic or cruise missile system. Ever since Ronnie 'Hellcat' Reagan came up with the idea of "Star Wars" twenty five years ago the US has spent about $100 billion trying to create an effective anti-missile missile. At least two things are wrong with the idea. One, the systems designed were to be used against intercontinental ballistic missiles (ICBMs) following predictable parabolas or "minimum energy" paths. To illustrate such a trajectory throw a stone up into the air. The initial energy input by your arm muscles and gravity control the stone's parabolic path (unless you believe in the "magic bullet" theory). The trajectory is mathematically predictable, making it theoretically possible but still actually difficult to intercept a ballistic missile traveling at hypersonic speeds. According to General James Cartwright, commander of the USAF Strategic Command who is paid to think about these things, the threat of attack by a enemy using ICBMs is no longer imminent--think Soviet Union and the Cold War. The US, despite its best efforts, has not been able to develop an ABM that is reliably accurate. Second and more importantly, no foreseeable enemy with the technical capability necessary to attack the United States at long range would use a ballistic system. To do so would be the modern equivalent of sending balloons. For example, North Korea which is just now developing long range delivery systems, could simply skip the step of a ballistic system, knowing in advance that the US has a shot at destroying a ballistic missile en route. Nuclear blackmail only works if your enemy knows your missiles are accurate and will reach their targets. Now throw a baseball at home plate and put a curve or slide on the ball, if you know how. As any hitter will tell you, the position of the ball at home plate is not very predictable especially if you mix up your throws with a knuckle or screwball pitch. Even more difficult to hit would be a baseball that breaks up into separate smaller baseballs, anyone of which could cross the plate for a strike. That is what a MIRV(multiple independent re-entry vehicle) missile can do. These are the types of evasive systems a resourceful enemy would use. The U.S., despite billions wasted on the tactically naive "Star Wars" idea, has no defense against weapons like these.
[photo: Minuteman III launch from Vandenberg AFB, CA]