The U.S. Air Force has asked for permission, and lots of money, to develop space weapons. The announcement was a bit vague, but what it actually refers to are a string of wargames and studies over the last decade that have revealed Americas increasing vulnerability in space. A large chunk of commercial, and military, communications are via space satellites. The military also uses dozens of spy satellites, not just for taking pictures, but for listening to electronic traffic below. Its also been noted that its getting cheaper and cheaper to go after large, expensive, communications or espionage satellites. Smaller satellites are the main weapon in space weapon, little suicide satellites who are directed to the general vicinity of their targets by ground controllers, then use onboard sensors to make the final run, and destroy a billion dollars worth of someone elses satellite. A slightly larger attack satellite, carrying more fuel for maneuvering, could carry small rockets, enabling it to take out more than one satellite. 

The problem with space warfare is that its so expensive to get up there (over $5,000 a pound), and once you are there, you need fuel to power small rockets that enable you to change orbit, and get near other satellites. If you are the United States, you defend your hundreds of communications and espionage satellites with your own little hunter-killer satellites that will go out and destroy enemy hunter-killers. No lasers or photon torpedoes, just shooting lead balls at each other. 

There are other options in space, like nuclear weapons and lasers, but the former is dangerous to have in orbit, and the latter is very expensive (requiring a lot of power) to operate. To date, nothing is more efficient at destroying a (preferably larger) satellite, than another (preferably much smaller) one smashing right into it. Smaller, cheaper and more powerful electronics have made it possible to build more effective and, most importantly, lighter, hunter-killer satellites. In any future war, Americas major vulnerability will be in orbital space. If a hostile nation builds even a few effective (it isnt easy to design and launch these things) hunter-killer satellites, the United States is in trouble. So the U.S. Air Force wants to get prepared, to build battle satellites to keep hostile hunter-killers away from American communications and espionage birds up there. The air force also wants to stake a claim on another large pot of money. Cash is power in the Pentagon, especially when its denominated in the billions. Fighting in space will cost a lot, a whole lot, of money.