President Obama plans to send 300 military advisers to Iraq to stabilize conflict . Julian Zelizer : History shows us that mission creep is difficult to avoid . The U.S. has been in Afghanistan for more than a decade, and the Taliban are still fighting there today. Zelizer : Obama could find himself forced to send more troops than he expected .
President Obama plans to send 300 military advisers to Iraq to stabilize conflict . Julian Zelizer : History shows us that mission creep is difficult to avoid . He says many operations - in Korea , Vietnam , Somalia - start small but end big . Zelizer : Obama could find himself forced to send more troops than he expected .