what is the name of this attack to the king's indian? have you seen lt?

I don't know if this idea has an opening name per se, but h3 or h4 are common ideas to White in King's Indian positions. I often play the h4 lines as White myself against the King's Indian Defense. I usually won't go for h4 this early though.

IIRC King's Indian players prefer c5 against the Samisch setup to e5; you've only considered black's response of e5.

No, not quite. I play the Saemisch variation a lot and am more than willing to play against the c5 lines too. I just put some moves onto the board to display the ideas White often goes for and why h4 is not unjustified. I did not intend to explain the theory I know; I wanted to simply address the op here. The op is rated about 1900 and probably knows a lot of theory; they were just asking if this h4 idea had an opening name. (I don't think it does, but h4 is a common motif in many of these lines and alternatively an early h3 is also common while subtly less aggressive)

I don't know if there is a name.

I think Simon Williams was the first GM advocating it, thus we could call it the Williams system (attack).

Personnally, against this kind of set up for white which neglects development, i switch to Benko mode.

For example :

In these structures, I don't think white's attck is dangerous, while black has quick counterplay.

Some nice examples :

Jobava has 3 games as white in databases, against Radjabov, Atalik, and a 2400. Scoring 3 points!

Each game, black played the Benko style and Jobava just took the pawns and won, but not convincing to me...

Rapport also has a crushing score (2.5/3) as white.

But they are (almost) the only one as white having good results...

Here the Jobava-Radjabov game :

Black could also play in Benoni fashion, like this game :

Once again, white was in trouble because black played active in centre.

Thanks a lot poucin, very helpful.  Yes I watched Simon's Killer DVDs on 1.d4, from those DVDs exactly was where I got the idea of playing this system with the white pieces, although I have been successful with it in online rapid games, now I see it would not be so easy in long OTB games, specially if black plays this Benko set up.  I will check it deeper with my chess engine anyways.  Thanks again! 

Thanks poucin! I got crushed as Black today in this system and seeing some of the ideas to counter it helps.

hikaru also recommended this line as it provokes h5 from black and the pawn on h4 almost thwarts any attack on the kingside

Also in a lot of Saemisch or Panno lines, h4 gets played after castling long with the idea of utilizing the Rook with a battery set on the c1-h6 diagonal. I'm in agreement that if Black can find a way to shut down the King side and try for okay in the opposite wing, Black can get some good play. I don't know if h5 is Black's best way to play unless he can achieve a v formation with pawns on d5-e6-f7-g6-h5. Hermann Grooten called it the v for victory formation in his book on positional play.