Bin Laden’s main objective – ridding Saudi Arabia of US forces. Why did Bush help him to achieve this?

‘Over the years, bin Laden and his fellow terrorists launched numerous strikes against U.S. targets with the stated design of getting American forces out of Saudi Arabia — including the twin embassy bombings in East Africa; the attack on the USS Cole in Yemen, and, eventually, 9/11.’
http://www.cnn.com/2003/US/04/29/wbr.saudi.base/
‘The United States has said that virtually all its [...]

What is our objective for war in the Middle East?

I heard that some politicians are suggesting that we start to get involved in Yemen now because of the C*I*A agent killings so there may be a threat in terrorism in Yemen. Are we like trying to completely take over the middle east or what?
why cant we find osama bin laden? I read a couple [...]