How can you tell when U.S. forces in Afghanistan are operating alone?

When they call it “the coalition”.

That’s not a joke. It’s just how things work in Afghanistan, where two separate forces with two separate command structures — one completely American, the other about half American — operate side by side under the command of the same U.S. general.

“When we say ‘coalition’, basically that means it’s just us,” a helpful U.S. military spokeswoman explained last month to a reporter who had just arrived in country after being away for a couple of years. “Otherwise, it’s the ‘alliance’.”

And it’s not just words.

“The alliance” and “the coalition” maintain completely separate press offices, each of which is often allowed to give only bits and pieces of detail about the same incident. The result can be a bit confusing.

First, some history.

The “coalition” refers to Operation Enduring Freedom, the U.S. (or, as they like to say, “U.S.-led”) mission ordered by President George W. Bush back in 2001 to catch Osama bin Laden and overthrow the Taliban.

Occasionally over the past eight years it has actually operated as a coalition, with contributions from Britain and other countries.

But these days, it’s strictly an American mission, with thousands of U.S. troops engaged in hunting insurgents, training Afghans and providing air support. (Well, maybe not quite strictly American: there could be a handful of British or Australian special forces in there too. But that’s a secret.)

“The alliance”, meanwhile, refers to NATO, which now leads the International Security Assistance Force, set up by the United Nations to provide a small number of mostly European peacekeepers for the capital after the fall of the Taliban, also back in 2001.

ISAF’s role gradually expanded until 2006, when it spread throughout the country, got a lot bigger and began fighting the Taliban, especially in the south and east. ISAF now includes contributions from around 40 nations, but these days the force is about half American and getting more so by the week as thousands of U.S. reinforcements arrive.

Since last year, ISAF and “the coalition” have both been commanded by the same U.S. General, David McKiernan, who is about to be replaced by another, Stanley McChrystal.

Because ISAF — unlike “the coalition” — actually IS a coalition, it has stringent rules on what its members let it say. When its troops are involved in an incident, ISAF won’t say what country they come from, or precisely where in Afghanistan the incident took place.

The defence ministry of each country is supposed to reveal that information back home, but that can take hours or even days. And if troops from more than one Western country are involved — not to mention Afghan soldiers and police — piecing details together can require the skills of Sherlock Holmes.

Here’s an example: a few weeks ago, “the coalition” said one of its soldiers was killed in an incident. NATO said four of its soldiers had died. Neither said where: somewhere in eastern Afghanistan. It took several hours and phone calls throughout Afghanistan and Riga to determine that three of the soldiers were Americans, two were Latvians, and that the incident was the same as one Afghan troops had already reported in Kunar province.

The investigation ended with a conversation that went like something like this:

Reuters: You’ve said one American was killed, right?

U.S. military spokeswoman: That’s what we’ve said, yes.

Reuters: And four NATO soldiers were also killed, right?

U.S. military spokeswoman: Yes, that’s what ISAF has said.

Reuters: And two of those NATO soldiers were also American?

U.S. military spokeswoman: Yes, I can confirm that.

Reuters: So actually three Americans were killed, yes?

U.S. military spokeswoman: Yes, that’s correct.

Confused? Join the coalition…