U.S. combat mission in Iraq only over on paper

A year ago on Thursday, President Obama announced in a press release the withdrawal of the last U.S. combat brigade from Iraq - in theory ending America's combat missions in Iraq.

However, as CBS News national security correspondent David Martin reports, some 46,000 U.S. troops remain in Iraq, and suicide attacks haven't completely stopped.

Martin says it's impossible to say the U.S. combat mission has completely ended. U.S. aircraft still conduct strikes against targets that threaten American forces, U.S. Special Operations forces still conduct night raids with Iraqi commandos, and although the U.S. Army brigades in Iraq are officially called "advise and assist" brigades, they are still fully prepared for combat.

Still, it's a much-reduced combat role in which the U.S. is supporting, rather than leading, the Iraqis. The best measure of that, says Martin, is that in the last 12 months, 59 American servicemen have been killed in Iraq, compared to 961 in the 12 months of 2007.

The remaining troops are supposed to leave by the end of the year - however, with violence flaring in Iraq again in recent months, and the instability of the government, questions have been asked as to whether America can really afford to leave.

It's widely expected that Iraq's leaders will ask for some number of U.S. forces to stay on - not the 46,000 there now, says Martin, but possibly 10 or 20,000 to help Iraq's military in areas where they still lack sufficient capability; mainly air defense and patrolling their borders.

If the number of U.S. troops is reduced to that level, it would leave the Iraqis to fight the war against insurgents on their own.

Al Qaeda in Iraq proved this week that it can still mount 42 separate attacks throughout the country in one day, and kill close to 100 people in the process, but on average there are only 14 attacks a day in Iraq now, compared to 145 every day at the height of the fighting.

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Al Qaeda in Iraq is down to about 1,000 fighters and supporters and is no longer a threat to overthrow the government, says Martin. The real threat is the Shiite militias which number in the thousands, and are backed by Iran.

The leaders of these groups live in Iran and they use Iranian-made weapons. Iran does not want the U.S. to succeed in Iraq, so those Iranian-backed militias will still be a threat, and as long as Americans are in Iraq they are likely to be targets.