You might want to read Christopher Andrew's authorised history of the British Security Service, MI5: The Defence of the Realm. The book describes details of some of the activities of Bolshevik agents in the UK in the years following the First World War.

I don't know of a similar history for the French Deuxième Bureau, but I suspect they faced similar issues. After all, the Bolsheviks in Russia advocated worldwide revolution.

The activities of Communists in Britain (and presumably also in France) were known, and were seen as a threat. Since the the leaders of new states of central-eastern Europe weren't actively attempting to subvert the main European powers, they were - presumably - seen as less of a threat in the 1920s.

Of course, that perception began to change in the 1930s ...

You might want to read Christopher Andrew's authorised history of the British Security Service, MI5: The Defence of the Realm. The book describes details of some of the activities of Bolshevik agents in the UK in the years following the First World War.

I don't know of a similar history for the French Deuxième Bureau, but I suspect they faced similar issues. After all, the Bolsheviks in Russia advocated worldwide revolution.

The activities of Communists in Britain (and presumably also in France) were known, and were seen as a threat. Since the the leaders of new states of central-eastern Europe weren't actively attempting to subvert the main European powers, they were - presumably - seen as less of a threat in the 1920s.

Of course, that perception began to change in the 1930s ...