Arguably this has been happening since the Cold War, as aircraft-launched missiles back then were designed to take out incoming cruise missiles. But in principle using something like an F-15 firing something like an AIM-120 is cheaper than using a Patriot, because the Patriot missile has to include a huge booster stage, a disposable radar, etc, while those can all be integrated into the plane instead in the case of an AMRAAM. In practice of course whether or not it is cheaper is dependent on the cost per flight hour of the plane and how many AMRAAMS you're making versus how many Patriot interceptors you're building. In that regard though, this _is_ new, because there's a fairly recently introduced missile called Advanced Precision Kill Weapon System (APKWS) that puts a relatively cheap seeker head onto a cheap otherwise-unguided rocket (I'm pretty sure the cost of an APKWS seeker + rocket is less than $50k), and those are cheap enough that you can send up an F-15 with hardpoints full of them and not worry nearly as much about letting loose several million-dollar missiles.