If US President Donald Trump’s refusal to re-affirm his country’s commitment to the crucial deterrence clause in the 68-year-old North Atlantic Treaty Organisation signalled a significant shift in the post-World War II order, his decision to exit the Paris climate accord unequivocally cedes the United States’ global leadership. Commentators have pointed to the fact that the deleterious effects of Mr Trump’s withdrawal from the Paris Accord, a key campaign promise linked to reviving coal-mining jobs, may be leavened by an extraordinary coalition, of 10 state governors, 187 mayors and many businesses, that has resolved to uphold the agreement’s target of