The Canberra Times

By Adam Lockyer

The recurring question surrounding last week's announcement of the permanent positioning of United States forces in the north of Australia was ''Why?'' What was the strategic logic behind the decision? The most common explanation has been that the US Marines will act as a ''tripwire''. If so, the deployment, as it has been announced, will be ineffective. A ''tripwire'' is a means of making extended deterrence more credible.

Extended deterrence is when a nation takes responsibility for the security of a smaller nation. In effect, the smaller nation (in this case Australia) comes under the security umbrella of a larger nation (here it's the US). The larger nation then tells any third country: ''Do not even think about hurting our little buddy, otherwise you'll have to deal with us too!'' The problem with extended deterrence is making the threat credible. This is where a ''tripwire'' comes in.

During the Cold War, for instance, America's extended deterrence strategy included West Berlin. The problem was, however, that if dozens of Soviet Divisions rolled over the border, the Soviets would have annexed the territory by the time Washington had time to respond.

At this point, it would have made little sense for any sitting American president to counterattack and risk a nuclear exchange that may result in the destruction of the US itself. West Berlin would already be under Soviet control and nuclear war wouldn't get it back. The Soviets knew this. So, how could the US make its extended deterrence over West Berlin credible? The answer was a ''tripwire'': the positioning of a US Army brigade in the territory. In any Soviet attack, the soldiers would be the first to fight and die. Being US soldiers they would die gallantly. But die all the same. Their deaths would give the US president no other option by to respond, even if it meant risking a nuclear exchange. The Soviets knew this. And so, the Soviet Union wouldn't risk invasion in the first place. The several thousand soldiers in West Berlin were a ''tripwire''.

Moscow was in no doubt that Washington would have to come to West Berlin's aid. This was an example of extended deterrence at its best. It is not ''rational'' for a US president to risk major war over a small and inconsequential ally. Tripwires get around this problem by giving the US president no decision - rational or not - to make. He must come to the ally's aid. But let's consider what make a ''tripwire'' effective. First, the president shouldn't have time to get his troops out of harm's way. They must be right on the border and be among the first to be fighting. Otherwise, the opponent may calculate that these troops will be redeployed after the fighting begins.

This is why American soldiers remain in the frontline on the Korean Peninsula. They will not have time to get out of the way. Second, they must be in sufficient numbers so any sitting president will risk the security of the US itself to respond. The stationing of 250 to 2500 marines in Darwin fulfils neither of these criteria. Any future president will possess a high degree of strategic autonomy to redeploy the forces - forwards or backwards. And, it's unclear that this force would be sufficient to risk a major war with today's China, let alone the far more potent China of the future.

A belligerent may calculate that the US's response will be ''limited''; for instance, to reinforce the troops already here rather than escalating to other theatres. If last week's announcement was intended to create a tripwire, it will be a poor one. This is not to say I disagree with last week's decision - only to suggest that any cogent reasons for the permanent stationing of US forces in Australia have nothing to do with deterrence. The best arguments for the decision are that it will act to reassure Australia and provide strategic depth for the US. Most analysts believe that any military confrontation between China and the US is both unlikely and in the very distant future. This has not stopped severe scaremongering occurring from certain sections of Australia and the US.

Indeed, listening to some of the commentary a ''Second Cold War'' is already upon us. Australia's anxiety originates from its abandonment concerns. The US concerns focus on the vulnerability of its forces in Korea, Japan and Guam to the next generation of Chinese aircraft and missiles. Last week's announcement will hopefully take a small step towards quelling these anxieties. Anything that can splash cold water on the small, but loud, hawkish minority must be considered a positive step. With any luck, this will allow Australia, China and the US to put security concerns to one side and get about doing what they all really want to be doing: deepening and widening economic ties to guarantee their future prosperity in the Asian Century.

Adam Lockyer is a lecturer in US politics and foreign policy at the US Studies Centre.