France finally joins up! (Sort of)

So the French are fighting in Iraq, . . . against the coalition! So says this BBC report. (Hat tip: Captain's Quarters by way of Abigail Brayden.)

Three Frenchmen have died fighting with insurgents against US-led troops in Iraq, reports say. The men, all of Arab origin, were killed in the country over recent months as the insurgency has flared.

. . . Authorities estimate that around a dozen Frenchmen of North African or Arab background have travelled to Iraq to join the insurgency.

While the BBC does clarify that they are of Arab origin--as if that excuses it ("This does not indicate a profile! We would never be so politically incorrect as to suggest such," says Whiskey)--they are all French citizens.

Although the French military never joined the coalition, are there any French aid workers or other French civilians assisting the coalition in Iraq? Might they be killed by their own countrymen? What laws do the French have about such things, if any?

We can assume that if American citizens were captured in Iraq fighting alongside the terrorists, we would charge them with treason. But what are the laws regarding American citizens joining a foreign war where the US isn't involved?

(I seem to recall that some Americans fought for France or England in WWII (or WWI?) before the US officially became involved. But I haven't time to look that up right now. Anyone?)