King's Indian Attack

The King's Indian Attack, often abbreviated KIA, is a setup in which White adopts the formation Black uses in the King's Indian Defense: Nf3, g3, Bg2, O-O, d3, Nbd2 and e4. After 1. Nf3 d5 2. g3, White puts off any central commitment with c4 or d4 and prepares the fianchetto, intending to build the e4 structure behind it. Because White is a move ahead of the Black version, the scheme can be handled more ambitiously. The same formation is also reached via 1. e4, chiefly against the French Defense or Sicilian lines with an early ...e6.

White's main plan is the advance e4-e5, which cramps Black, gains kingside space and creates attacking chances against a castled king. Unlike in the French, the e5-pawn is held by pieces such as Nf3, Re1, Bf4 and sometimes Qe2 rather than by a pawn on d4, so Black lacks the usual d4 target. The attack then continues with moves like Nf1, h4, N1h2 or Ne3, h5 and g4, while Black typically seeks counterplay by advancing the queenside pawns. Black's recurring difficulty in the ...e6 structures is the c8-bishop, shut in behind its own pawns; freeing it with a later ...e5 leaves Black tempi behind a standard King's Indian position.

The most frequent replies are 2...Nf6, 2...Nc6 and 2...c5, the Sicilian Variation. Classical Franco-Sicilian positions arise after 2...Nf6 3. Bg2 c5 4. O-O Nc6 5. d3 e6. After 2...c5 3. Bg2 Nc6, the French Variation, Black can instead choose the Reversed King's Indian with 4. O-O e5 5. d3 Nf6, taking over the space-gaining role of White in a King's Indian. Other approaches develop the queen's bishop outside the pawn chain: 2...Bg4 is the Keres Variation, while after 2...Nf6 3. Bg2 c6 4. O-O, 4...Bg4 is the Yugoslav Variation and 4...Bf5 yields a reversed London System. Rarer options include the Double Fianchetto with 2...g6 and the Omega-Delta Gambit with 2...e5.

The system spread at grandmaster level in the 1950s as an offshoot of the King's Indian Defense's popularity. Bobby Fischer, chiefly early in his career, used it alongside Botvinnik, Smyslov, Petrosian, Stein, Vaganian, Morozevich and Aronian, and the trainer Mark Dvoretsky advocated it. It is now relatively rare among grandmasters, Bassem Amin being its most regular high-level exponent, but it remains a club favorite thanks to its repeatable plans. Engines rate the position after 2. g3 as roughly balanced, and White scores well in online games.