In the past, the imperialism of the West, like that of the rest, was often difficult - for the doers as well as for their victims - but western states were, nonetheless, usually able to dispatch forces overseas against non-western peoples without any fear of being attacked themselves. That kind of immunity is probably now a thing of the past.
Postcolonial critics are, I suspect, wrong when they argue that the mass of British people still mourn the loss of empire. But Britain's politicians - and its Foreign Office - have found it hard to adjust to the loss, not so much of onetime colonies as of the global clout the colonies once afforded.