TERRORISM STILL A TOP EXTERNAL CHALLENGE

President-elect Barack Obama takes questions from reporters during a news conference in Chicago, Monday, Dec. 1, 2008, with, from left to right: Attorney General-designate Eric Holder; Homeland Security Secretary-designate Janet Napolitano; Defense Secretary Robert Gates; Vice President-elect Joe Biden; Secretary of State-designate Sen. Hillary Rodham Clinton, D-N.Y.; National Security Adviser-designate Ret. Marine Gen. James Jones; and United Nations Ambassador-designate Susan Rice. (Xinhua/Reuters Photo) Photo Gallery>>>

    Earlier this month, Obama acknowledged that the U.S. national security challenge is as urgent as the financial turmoil.

    The recent brutal attacks in Mumbai reinforces the theory that terrorism will still be the United States' top external threat.

    Combating terrorism, for Obama, would mean wrapping up the war in Iraq and focusing on Afghanistan.

    Iran, the Korean Peninsula and the Middle Eastern peace process will also be high on his agenda, though none of them are easy tasks.

    Moreover, as history shows, every new president will probably face an unexpected security issue soon after taking office.

    In their first year of presidency, Clinton got Somalia and Bush was ambushed by the 9/11 terror attacks.

    Time after time, an unexpected turn in world events rewrote a president's agenda and tested his ability in crisis management. Will Obama be an exception?

    Finally, the greatest of all challenges may be how America deals with a fast changing geopolitical map.

    A new U.S. intelligence report says the decline of U.S. power and the emergence of a multipolar world will be a certain trend in the next two decades.

    Under such a scenario, it would certainly be much harder to "enhance the U.S. leadership and change the world."