December 23, 2009: The U.S. Army and Marine Corps are well aware of the big differences between operating in Iraq and Afghanistan. Thus new training programs, often complete with Afghan style villages, staffed by Afghan-Americans trained to role-play what the troops will encounter in the real Afghanistan. This helps.

But this isn't much help to the thousands of troops who have sent straight from Iraq to Afghanistan. When terrorist activity in Iraq plummeted over 90 percent more than a year ago, there were some doubts, and fears that the bad guys would make a comeback. They didn't, although they keep trying. The few attacks they can still carry out are done at times and places calculated to get maximum media coverage. Meanwhile, the Iraqi military and police took over complete control of security earlier this year. That has left U.S. troops without much to do. So, while the U.S. combat brigades still assigned to Iraq remain in place (largely restricted to their new, suburban, bases), over 3,000 support (transportation, engineering, maintenance and communication) troops have been quietly sent to Afghanistan. Some are ordered to Afghanistan shortly after they arrive in Iraq. For many of these troops, it's their first time in Afghanistan, after having served two or more tours in Iraq. While U.S. troops have been in Afghanistan since late 2001, for most of that time, there were only about 20,000 of them there. Now it's over 60,000, and rapidly expanding to 100,000. In Iraq, a much more developed country (more roads, access to the sea and much closer to Europe), there have been 150,000, or more, American troops there since 2003. U.S. bases in Iraq are well equipped, the danger is low and there's not a lot to do. In contrast, the bases in Afghanistan are sparse, there's a lot more violence (although still only about half as much as there was in Iraq during 2005-7), and a lot more to do. So the U.S. troops arriving in Afghanistan straight from Iraq encounter a bit of culture shock.

Most of the troops leaving Iraq, are those that have completed their twelve month tour of duty, and are heading back to the United States, where they will remain for at least a year.