Some rocket scientists in this thread seem to be having the time of their lives talking about stuff they know nothing about. The altitude of intercept is a very variable thing, I'm pretty sure future tests will reach much farther heights. But the thing is, you need to have a decommissioned sat in place that you're willing to lose, and which isn't gonna create too much of a problem with regard to space debris.
Taking out sats at lower altitudes means the debris will most likely burn up in the atmosphere instead of sticking around in orbit, posing massive hazards to spacecraft. That's why the Chinese ASAT test drew so much ire.
But really, hitting sats in higher orbits isn't that much of a problem, you just need more fuel is all. Infact as someone already pointed out, hitting sats in lower orbits is tougher, as they are moving at much faster speeds.
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But the real significance here is that we demonstrated an ability to take out a fast moving sat in LEO with a hit-to-kill KKV (kinetic kill vehicle). Only the 4th country to demonstrate this capability. And this is only the first step.
An ASAT weapon is no mean feat, and on top of that, a ASAT with KKV warhead is an even bigger achievement.
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Now onto the strategic significance...just like there was Nuclear non-proliferation treaty (NPT), there will also be a binding space warfare NPT in future. You can mark those words.
But now India already got its foot in the door with regard to the space warfare NPT. In future, India will enjoy the kind of power the present NPT-signatory countries (P5 UNSC permanent members) enjoy as against the non-NPT ones. People who follow geopolitics will understand the aspects at play here very well.
Some more pics:
