It is possible that they do not have conclusive evidence of Iraqi connection even though evidences gathered so far stronly pointed toward Iraq. Naturally, the production of this bioweapon is a top secret program. CIA/FBI may not know what is going on in Iraqi lab until you find a person who worked there or go to that place themselves. That may be what they are doing now. Try to find an employee who would defect or send a team of SpecOps to suspected sites. If this is true, the timing of war also depends on the success of this endeavor. Once this is turned out to be true, Arab solidarity can mean nothing when it comes to put pressure on America.
I don't think it was Iraq, or it would have come out sooner. They have been looking only for Pakistanis so far for the perps. They looked at a house where 4 Pakistanis lived in Trenton, and went into two Pakistani doctors' homes in the suburbs of Philadelphia. Australian newspapers reported they were looking for Pakistanis and only Pakistanis. I think it is quite possible that the I.S.I. created this for bin Laden, and they didn't want that fact coming out while Musharraf was co-operating. So they floated the lone nut right-winger story, because it worked so well in the Okalhoma City bombing.