It is as if
Sharon wanted to weaken the only Palestinian moderate enough to have recognized Israel's existance and to want peace (Arafat) so that the only Palestinians left to argue with are those who want Israel's destruction, justifying his attacks into the Palestinian areas.
We've learned how machiavelian Sharon was with his visit to Jerusalem's wall leading to his election as prime minister. Sharon knows he'll get the US unconditional support, especially if the only Palestinians he wants to be confronted with are the most extremist.
Raoul