The troops will form 'belts' around volatile cities like Mosul, where some fear gains in stability will be lost when US troops pull out on June 30.
The fatal shooting of a young man on a crowded downtown street illustrates why Americans could have trouble completely leaving this troubled provincial capital.
As US prepares to withdraw troops from major cities, bombings in Baghdad and near Kirkuk have the country on edge.
An Iraqi government spokesman's opening line was meant comically, but rang true. The country's military leaders and officials are increasingly emphasizing Iraqi independence.
'What is a city' is one question the US and Iraq must answer as they try to balance a requirement that US combat forces withdraw from cities next month and the need for US help to maintain security.
June's pullback is part of the phased withdrawal of US forces. Will it jeopardize hard-won security gains?
US intelligence officials do not see a reversal in security gains, but Iraqi political maneuvering could affect decisions to keep US troops in trouble spots.
Easter Sunday this year marks the return of Christians to several of Baghdad's most battered neighborhoods.
The attack came in Mosul, the most dangerous city in Iraq.