The problem in Iraq now appears to be the (perhaps justified) fear on the part of many Sunnis that after decades of their dominating the Shiite majority, it may be payback time. So in order to not support the insurgency, they need assurance that their interests will be protected by inclusion in the government. Of course they may have an unrealistic view of what their rights are. And now, the bombing of the Dome has strengthened the Shiite faction who feel the Sunnis have been coddled long enough.

And the US ambassador's recent threat that the US wouldn't support sectarian rule in Iraq (a statement probably geared to US domestic consumption) may well not have helped.

The Sunnis, concentrated in mid-Iraq, are only too aware their area is oil-poor, in contrast to the rest of the country.

And of course the Kurds want continuation of a de facto Kurdistan--and want oil-rich Kirkuk included.