UTM traffic redirection between 2 UTM in different offices

I have the following scenario:

2 offices in different countries connected via leased line directly to each other. Each office has its own UTM and Internet connection.

Now, I want certain web traffic from UTM B in office B to be redirected to the UTM A in office A via leased line and use the Internet line from Office A (instead of using internet link from Office B)

I tried adding policy route into UTM B to redirect certain IP to UTM A, and added a NAT and firewall rule on UTM A to allow Office B access the internet.  At the moment I am not having any luck - is there a simple method to do this or am I missing something?

Thanks.