Introduction
Department of homeland security is one of the reactions of 9/11 attacks on United States of America. It is a cabinet department of federal government of USA. It was formed on November 25, 2002. DHS was mainly formed to fight terrorism. DHS imbibed Immigration and Neutralization Services in March 2003. After assuming its duties, DHS divided the enforcement and services functions in to two different new agencies. Those two new agencies are named as immigrations and customs enforcement and citizenship and immigration services. Investigation division and intelligence gathering unit of Immigration and Neutralization services and custom services were merged to form Homeland security investigations. All these are designed to make the homeland United States of America save and secure. It was formed to assure the people of USA to secure them from any kind of terrorist related activities and also from threats like illegal immigration. The five core missions of homeland security are as follows. (Smith, 2006)