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Protesters shoot silly strings and blow bubbles while demonstrating in front of Boeing corporate offices as a part of the NATO summit Monday, May 21, 2012 in Chicago. (AP Photo/Nam Y. Huh)

Protesters swarm on final day of NATO summit

Demonstrators launched another round of protests May 21 in the final hours of the NATO summit, marching through an unusually quiet downtown Chicago to the headquarters of Boeing and President Barack Obama's campaign.