KID with Ne1

Against d4, a high majority of my opponents play the King's Indian Defense (KID). Recently, I switched from lines with 9. Nd2 to 9. Ne1. Here is an example of the first moves of one of my games:

On the 13th move, which is the best continuation? Nd3, a4, b4, or Rc1?

Thanks!

Either 13.Rc1 or 13.g4. It depends on the type of position you want to play.

But 13.Nd3 also has followers (Shirov, Volokitin).

Korchnoi's 13.a4 is out of fashion, while 13.b4 is rather a useless move, in most cases.

Good, you're also playing 9. Ne1 (a couple months ago, I switched from the Bayonet Attack). I usually play 13. Nd3, followed by b4 and c5 ASAP. Another plan is Nb5, intending to jump to a7 and trade the knight for black's powerful LSB. Also, if  13.Nb5 a6 14. Na7 Rxa7 15. Bxa7 b6, trying to trap the bishop, you have 16. a4! followed by a5.

I just came along this page on chessgames.com which seems to have some games worth looking at.

I've never seen 13. g4 before. Can you tell me the ideas behind it after fxg3? Thanks!

The idea is rather simple: On 13...fg3 14.hg3 Ng6 15.Ng2! white easily holds black's initiative on the K-side, has some nice squares for the g2 knight, while he can proceed with c4-c5 later, when Black is short of ideas in the K-side. Ruslan Ponomariov has been playing the white part quite succesfully the last couple of years. The original idea of the move belongs to (no surprises here) Svetozar Gligoric, who has done some analysis of it some forty five years ago.

Anyway, this g4 variation is rather irrelevant, as Black can play 12...h5 instead of 12...g5, when most obviously 13.g4 is not a very good option anymore.

12...h5 also has a dark side though, but I'd rather not reveal everything... 

My DB shows black does worse with 12.... h5 though than with 12... g5 . After 12...h5 white is scoring heavily with both 13 a4  and 13 Rc1 

13.Rc1 will most likely transpose to 12...g5 13.Rc1 after a couple of moves, but it's certainly true that 12...g5 13.a4 is usually answered by 13...Ng6 14.a5 Rf7 (or 14...Kh8), not 13...h5. There is quite a bit of transpositional ideas here, which you'd probably like to explore further.