The United States is bankrupt. The government refuses to pay its bills. The US currency is no longer the 'be-all and end-all' of international currencies. Notwithstanding Apple, Microsoft and other entrepreneurial start-up companies, US economic clout is on the wane.
Ok, so the US is not really bankrupt – it can keep printing (and debasing?) more paper currency notes which the rest of the world happily purchases in ever growing amounts. Economic stability equals a free trade environment predicated on trust in the USD.
The rest of the world includes Singapore.
Singapore's foreign currency reserves, one of the largest pools of capital in the world are biased towards the US Dollar (USD). From Temasek Holdings to the Government of Singapore Investment Corporation (GIC), Singapore's stake in international economic stability is great. Singapore is not alone. China – the largest single owner of US government debt – has a lot riding on USD stability.
The day China stops buying US debt, the USD may collapse.
Result: China becomes much less wealthier, on paper at least. Moreover, the US will be unable to keep importing goods from China because it cannot pay for them in the 'new, debased' USD. In turn, this leads to social problems within China as Chinese factories reduce production and lay off workers. Consequently, Chinese consumers, including travellers, decrease consumption and the world suffers more ... and the vicious cycle continues.
Of course, global politics are not so simple. Despite a gradual shift away from US dependencies, the world needs the US to behave responsibly. International stability continues to rest on the US, economically and politically. Shutting down government because of domestic political squabbles is not responsible. It smacks of 'Banana Republic' politics and politicians. The US looks more and more like the Third World countries it chooses to lecture (and bomb when they don't listen) about governance on a regular basis.
The world entered a new socioeconomic era some years ago. The post World War Two Bretton Woods and Cold War orders have wasted away. However, the replacement paradigm has yet to be defined. At least for the next several decades the world will continue to watch US domestic politics as if it were their own.