How can I break the King's Indian Attack?
I think my h7 square is vulnerable to attack; what is the best way to break this strategy?
I doubt that the King's Indian Attack can be 'broken'. It's a very solid position that White takes the time to setup, if Black is not careful, White may be able to gain space on the kingside, with moves such as e5, and develop dangerous attacks if Black has castled there.
As for h7 being weak, many things need to happen from Black in order for this to be realized (such as a semi-open h-file, Bg7 has been exchanged, in which case it is h6 that is weaker), so there may not be anything there worth exploring.
I can't comment on what the 'best' defense would be, but there are many good ones, one such is the Botvinnik Sytem. Black makes use of the extra available tempi to set up a strong and flexible defense. The typical structure would be pawns at c5, e5, d6, g6 and pieces at Nc6, Nge7, Bg7 and 0-0. Black has a firm control over the d4 square and can potentially break with either
I recently faced a very similar problem when I organized a King's Indian Attack themed blitz tournament at my club. The problem is that it takes quite a few moves to establish White's KIA position and I had to find moves for black that preserved Black's flexibility in light of the many Youtube videos out there that promise to "crush Black with the KIA" :-).
The solution I came up with was to follow a line recommended by England's "Ginger GM", Simon Williams in his series of videos on the French Defence. It goes like this:
[fen ""] 1. e4 e6 2. d3 d5 3. Nd2 c5 4. Ngf3 Nc6 5. g3 g6 6. Bg2 Bg7 7. O-O Nge7 8. Re1 b6
There are a number of ideas here.
Of course this does not refute the KIA but it does give a flexible and rich way to combat White players who bang out the first 10 or 12 moves like an automaton.
So far, I’ve had success with the Pachman System, d5 g6 Bg7 e5 Ne7. If they play d4 before you can get the e5 off, you can go for Nf6, Nd7, and Nb6, allowing you to capture any c4 pawn, and get a good position while they recapture.