The US Army is considering having two separate medals for operations in Afghanistan and Iraq. The justification behind the two different medals is that the missions are significantly different, and that service in operation is not necessarily the same as service in another.
There are several issues at work here:
1. The precedent for expeditionary medals in the Army is murky, but still seems to lean against this. The soldiers that stormed the beaches of Normandy in June, 1944 certainly had a more difficult mission than those welcomed, in August 1944, by the local French authorities during Operation Dragoon in southern France. Yet both groups of soldiers were awarded the Allied Expeditionary Force medal for Europe. Ditto the soldiers that stormed the Philippines and those that fought overland in India and Burma.
2. Politically, the decision may come back to haunt the administration, who have insisted that the two missions were part of an overarching "Global War on Terror" (GWOT). By attempting to tie Iraq and Afghanistan together, the administration clings to the hope that the American people will see the liberation of Iraq as somehow relevant to the retaliation the public sought for 9-11. By approving two different medals, the administration would be recognizing publicly that they are different missions and should be treated as two different operations, instead of an overarching "Global War on Terror."
3. One of the reasons that the Army is pushing for two different medals is that the troops themselves have asked for some sort of differentiation between the two missions. The soldiers see the missions as completely different, and do not want them lumped into one big 'campaign.' This is especially true for National Guard soldiers. Active duty soldiers accumulate medals for waking up in the right bed, but National Guard soldiers have far fewer medal opportunities, and the awards tend to mean more to them. Also, National Guard soldiers have to go home and explain to their civilian buddies what their medals are for, and how they were earned.
4. Complicating the "two medal" course of action is this: soldiers participating in the GWOT in the Philippines, or Djibouti, or Europe, could be left out in the cold if the medals are authorized specifically for Afghanistan and Iraq. Although soldiers in Central Asia (Uzbekistan, etc) would probably get rolled up in the Afghanistan medal, soldiers in Europe are supporting everything. And some soldiers are supporting from Europe, while others are just stationed there because that's where their unit is. And as Islamic terrorists start to surface in the Balkans, soldiers on UN/NATO missions there could conceivably tie themselves into the GWOT.
One medal covers everyone. But the troops want differentiation. Differentiation may be politically uncomfortable for the party in power. But the logistics of multiple medals complicate the rules of 'who earns what.' And in all of that, some soldiers are going to end up with about four new medals, ensuring that yet another American sergeant looks like a Latin American dictator in his dress uniform.