Consider the following statements regarding Susan Strange's book 'Retreat of the State':
I. It fundamentally challenged the Westphalian understanding of state sovereignty as an unimpeachable constant in international relations.
II. Big businesses, drug barons and accountants do not encroach on the sovereignty of the state.
III. Power of the state is diminishing in an increasingly interconnected and globalised world.
IV. State has been able to keep the non-state actors in check and thus its sovereignty remains unchallenged.
Which of the above-mentioned statements is/are true?