A mystery photo from WW1

As we approach the centenary of WW1 one of my associates posted a picture that had been in his family archives.

As I had a herd of nerds on Saturday evening I printed it off and tossed it into their midst for identification.

I thought the central soldiers were Russians, and that the guys in service caps to the sides were Americans.

BUT when printing it off A4 size, you can see the service caps have tassles, which is not characteristic of Americans in WW1. The collective suggested they might be Greek or Belgian. The Osprey book “Armies in the Balkans 1914-18” p46 has a good likeness, with a picture of six troops from different nationalities shown.

A Belgian in an American Greatcoat which seems similar to the greatcoat worn in the original photo.

Belgian soldier with cap tassle.

BUT, the pictures I find for the Russian Expeditionary Force to the western front show them in Adrian helmets.

So could this still be a photo from Salonika where the Russians wore their own (national) uniforms, with Greek troops ?

Answers please !