SCENARIOS - Iraq steps into precarious but sovereign unknown

By Michael Christie

BAGHDAD (Reuters) - Iraq takes a major step towards reasserting its sovereignty on Tuesday when U.S. combat troops hand urban areas over to its relatively untested police and soldiers.

Will the end of one aspect of the "surge" strategy -- the ramped-up deployment of U.S. forces in militant strongholds that helped drive al Qaeda and other fighters underground -- lead to a collapse in security?

WILL VIOLENCE SOAR?

It is highly likely that insurgents will increase their attacks following the departure of U.S. combat troops from city centres, both U.S. and Iraqi officials say.

Some militant groups may want to create the impression that they deserve the credit for driving out the occupation forces.

The fact that the partial withdrawal has been dictated by a bilateral security pact agreed last year between the United States and Iraq is immaterial to them.

Some of the insurgents may also think Iraq and its population will be more vulnerable once the Americans pull back to their bases, and that they have a better chance of reigniting widespread sectarian bloodshed through massive bombings.

There have been indications, however, that insurgent and militant groups have lost the capacity to keep up the momentum.