even satellites in low earth orbit can be engaged by weapons such as SM-6.
Moving into a whole new area of tracking and identification let alone engagement. Plus we are moving into an era of cubesat sized constellations in their thousands (even the UK is going to have one) with almost instant launch and replace capability.
Boeing Pelican would probably be the cheaper solution - particularly for the Pacific island chain theatre....
https://en.wikipedia.org/wiki/Boeing_Pelican