From Der Spiegel:

> 
> Auf ostdeutsches Drängen **hin** führte Prag scharfe Kontrollen an der Grenze zu Ungarn ein.
> 
> 
> 

The sentence seems to be complete without the *hin*:

> 
> Upon East German pressure, Prague introduced stricter control at the border to Hungary.
> 
> 
> 

What is the *hin* doing here?