MELBOURNE - According to the United States Federal Reserve, Americans' net worth has fallen 40 per cent since 2007, returning to its 1992 level. Progress towards recovery will be slow and difficult, and the US economy will be weak throughout the run-up to November's presidential and congressional elections. Can any incumbent - and especially President Barack Obama - win re-election in such conditions?

To be sure, the blame for America's malaise lies squarely with Obama's predecessors: Bill Clinton, for encouraging the Fed to take its eye off financial-market supervision and regulation, and George W. Bush, for his costly wars, which added massively to US government debt. But, come Election Day, many (if not most) Americans are likely to ignore recent history and vote against the incumbent.

Given this, it would not be surprising if Obama and others in his administration were seeking non-economic issues to energise his campaign. National-security problems in general, and the challenge posed by China in particular, may be shaping up as just such issues.

Obama's foreign and defence policies have been assertive, to say the least, especially in the Middle East and the Pacific. He has sanctioned far more unmanned drone strikes than Bush did; extended the security services' intrusion into Americans' privacy; allowed the CIA to continue its rendition program; approved trials of accused terrorists by flawed military tribunals; and has not shut Guantanamo Bay.

Moreover, the US is increasing its troop presence in the Pacific at a time when it already has more military force in the region than all other countries combined. Six aircraft carriers, with their accompanying support vessels - indeed, 60 per cent of America's entire navy - are now stationed in the Pacific.

In addition, Obama's administration has been conducting talks with the Philippines to increase and enhance naval cooperation. And Singapore has been persuaded to host four advanced naval ships. Australia has established a base for marines in Darwin and another for unmanned spy planes on the Cocos Islands.

That is not all. In a move that has received little or no publicity, congressional Republicans added a clause to the Defense Appropriation Bill for next year requiring the Obama administration to consult with countries in the Western Pacific about stationing even more forces - including tactical nuclear weapons - in the region. Senator Richard Lugar has advised me that since there has been little or no objection to the amendment from the White House, he sees no reason why it will not pass the Senate.

At a recent security conference in Singapore, US Secretary of Defense Leon Panetta emphasised the American military build-up in the region. Afterwards, he went to Vietnam, allegedly for discussions about the US Navy's use of Cam Ranh Bay, a major American base during the Vietnam War.

The US, like Australia, denies that all of this adds up to a policy of containment aimed at China. But few in the Western Pacific see it that way.

Panetta's visit to Vietnam followed hard on US Secretary of State Hillary Clinton's visit to Beijing for strategic and economic talks. Those talks seemed to go well, but it is becoming increasingly clear that the US is pursuing a two-track policy: talks, yes, but a build-up and repositioning of US military power in the Pacific just in case.

All of this is happening at a time when China is preparing for a change of leadership. I happen to believe that the political transition will occur smoothly. Others suggest that it will be - and already is - a difficult period of turmoil and uncertainty.

The Obama administration may believe that toughness directed at China will generate electoral support in the US. During major international incidents or crises, America has seldom voted against an incumbent president. But has he properly reckoned with how provocative his policies are to China?

None of this is meant to suggest that the Pacific region does not need America. But, while America obviously has a significant role to play in the region, the US should have learned by now that its political objectives are unlikely to be achieved by military means.

The Chinese themselves do not want the Americans to leave the Western Pacific, as that would make smaller countries on China's periphery even more nervous about Chinese power. China is mature enough to understand this; nonetheless, a major US military build-up throughout the region is another matter.

These are dangerous days, not only economically, but also strategically. We really do need to ask whether Obama is trying to play a China card to shift the electoral scales in his favour. If that is his intention, it is a move fraught with great danger.

Australia should be saying to the US that it will have none of this. I would sooner abrogate the Anzus Treaty with New Zealand and the US - that is, I would sooner end defence cooperation with the US - than allow nuclear missiles to be sited on Australian territory.

The current Australian government would not take such a step, and the opposition would be unlikely to do so as well. But more and more Australians are beginning to question the closeness and wisdom of our strategic ties to the US. Perhaps our best hope for stability and peace lies in China's refusal to be provoked. The Chinese understand the game being played. I suspect that they will remain on the sidelines during the US election campaign.

Malcolm Fraser is a former prime minister of Australia.