ROUGH CUT (NO REPORTER NARRATION)br br U.S. President Barack Obama urged Americans upset by the Missouri grand jury decision not to indict a white police officer for the shooting death of an unarmed black teenager to move forward constructively to achieve real change.br br During an appearance in Chicago planned for immigration, Obama said the reasons for the anger were justified but condemned the violence that broke out after the decision was announced.br br "The frustrations that we've seen are not just about a particular incident, they have deep roots in many communities of color who have a sense that our laws are not always being enforced uniformly or fairly," Obama said.br br The president added that in addition to the federal investigation he ordered outgoing Attorney General Eric Holder to work with local law enforcement agencies and community leaders to find specific steps that will build trust in communities.