is increment on shared ulong atomic operation?

[Charles Hixson via Digitalmars-d-learn]

If I define a shared ulong variable, is increment an atomic operation?
E.g.

shared ulong t;

...

t++;

It seems as if it ought to be, but it could be split into read, 
increment, store.

I started off defining a shared struct, but that seems silly, as if the 
operations defined within a shared struct are synced, then the operation 
on a shared variable should be synced, but "+=" is clearly stated not to 
be synchronized, so I'm uncertain.