King's Indian Attack (KIA) purpose?

Question

The King's Indian Attack usually starts with the following below

[FEN ""]
1.Nf3 d5 2.g3

However, I do not fully understand what this opening is trying to do. I understand that White might try to take control of the center later with d3 and then e4, but are there any other variations of this opening that can be played aggressively or defensively?

Answer 1

Let's face it, 1. Nf3 and 2. g2 isn't going to cause a strong player with the Black pieces any problems. Importantly, though, White isn't going to lose the game because of these moves either.

White has to be careful because Black can take the center. Any careless moves by White can leave them without effective pawn-breaks, meaning that they'll be low on space and Black will probably take an advantage. If the White player knows their stuff, though, they can maintain their pawn-breaks and eventually counter-attack the Black center.

If Black chooses not to take the center but instead gain Queen-side space, well, White is already on the way to playing f4 and h4, possibly with a King-side pawn-storm. That's not essential, though, as depending on what Black does, White can often transpose into e4, d4 or c4 systems.

Whilst not immediately challening Black, this opening therefore gives White a clear middle-game plan to execute whilst bypassing, in most cases, Black's preparation - not a terrible combination... It also invites Black to over-extend, get over-confident, or otherwise take a center that they may not know how to handle. For this reason, I've heard the KIA described as a good opening against a weaker opponent (and a terrible opening against a stronger one!).

Answer 2

The move order 1. Nf3 and 2. g3 is an extremely flexible asset, often used in elite level. Below I break down some ideas.

Avoiding early variations

White waits for Black’s early moves, and later transposes to a known line. For instance, one of the early main lines of the Catalan is:

[fen "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1"]

d4 d5 2. c4 e6 3. Nf3 Nf6 4. g3 dxc4

Studying the line above requires a huge amount of time and effort. However, if White opts for the following order:

[fen "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1"]

Nf3 d5 2. g3 Nf6 3. Bg2 e6 4. O-O Be7 5. d4 O-O 6. c4

We reach the tabiya of the Catalan, cutting off a huge amount of theory (although Black may for example play 5... b5 to "punish" the late advance of the c-pawn).

Playing Black's defenses in reversed colors

A different approach, but also heavily played, is to “play as black with a tempo up”, especially for players who enjoy the Benoni, Grunfeld, King's Indian Defense, amongst others, with Black.

White invites Black to take control of the centre with 1. Nf3 2. g3 to transpose to known Defenses in reversed colors:

[fen "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1"]

Nf3 c5 2. g3 d5 3. Bg2 Nc6 4. c4 (4. d4) (4. O-O e5 5. d3) 4... d4)

King's Indian Attack (KIA)

The KIA may arise generally if Black plays the typical pawn setups below.

[fen "8/pp3ppp/4p3/2pp4/8/8/8/8 w - - 0 1"]

or

[fen "8/pp3ppp/3pp3/2p5/8/8/8/8 w - - 0 1"]

The tematic KIA manouver

White launches a tematic attack to the kingside, following a sequence of moves which can be reproduced almost automatically in several variations. This doesn't necessarily mean that these moves are best. Indeed, the engine's evaluation is often favorable to Black, but neutralising White's attack is not trivial–it requires an accurate defensive setup and counterplay at the queenside. 1. Nf3 2. g3 3. Bg2 4. O-O 5. d3 6. Nbd2 7. e4 8. Re1 9. e5 10. Nf1 (10. Qe2) 11. h4 12. Bf4

[fen "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1"]

Nf3 i9 2. g3 i9 3. Bg2  i9 4. O-O i9 5. d3 i9 6. Nbd2 i9 7. e4 i9 8. Re1 i9 9. e5 i9 10. Nf1 (10. Qe2) i9 11. h4 i9 12. Bf4 i9

Example game

[fen "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1"]
[Event "Sousse Interzonal"]
[Site "Sousse TUN"]
[Date "1967.10.15"]
[EventDate "1967.??.??"]
[Round "3"]
[Result "1-0"]
[White "Robert James Fischer"]
[Black "Lhamsuren Myagmarsuren"]
[ECO "A07"]
[WhiteElo "?"]
[BlackElo "?"]
[PlyCount "61"]

e4 e6 2. d3 d5 3. Nd2 Nf6 4. g3 c5 5. Bg2 Nc6 6. Ngf3 Be7
O-O O-O 8. e5 Nd7 9. Re1 b5 10. Nf1 b4 11. h4 a5 12. Bf4 a4
a3 bxa3 14. bxa3 Na5 15. Ne3 Ba6 16. Bh3 d4 17. Nf1 Nb6
Ng5 Nd5 19. Bd2 Bxg5 20. Bxg5 Qd7 21. Qh5 Rfc8 22. Nd2 Nc3
Bf6 Qe8 24. Ne4 g6 25. Qg5 Nxe4 26. Rxe4 c4 27. h5 cxd3
Rh4 Ra7 29. Bg2 dxc2 30. Qh6 Qf8 31. Qxh7+ 1-0

This is obviously a very simplistic approach to the KIA, which might be useful to <1800-rated players. To learn more, I find Sergei Movsesian's games very instructive. He is a KIA expert, and his repertoir is mostly based on this openning.