With a POD starting no later than Januari 1st 1915, have a major balkan war started by Italy and expanded by Hungary.
Basically, a fascist Italy attacks Yugoslavia in 1935, instead of Ethiopia. Hungary soon sides with Italy in this in order to gain new territories, as a result, Romania and Czechoslovakia declares war to Hungary. In turn, Poland and Bulgaria declares war to respectively Czechoslovakia and Yugoslavia.
The Soviet-Union sides with the little entente and Germany sides with Italy/Hungaria/Poland/Bulgaria, some speculates the war might escalate into a fighting between them and should that happen, the Anglo-French would remain non-belligerent although they could indirectly support the loosing side to avoid it collapsing completely.
How would it comne to that?
Since the POD is in 1915, the Soviet-Union doesn´t need to be Stalinian or even fully communist, although trotsky cannot be in charge either. Germany does not need to be National-Socialist but it cannot be communist or neo-kaiserist.
Italy is still fascist with, Mussolini leading the fascist takeover (unless you can find a serious alternate fascist leader of course) but does not need to have Mussolini in power by the time the war starts, even if Mussolini is still in power his atitude can be somewhat different due to the different history.