It is the Government's job to react to world events. It is not its job to over-react to world events.Fortunately, in its advice to business and industry following this week's dramatic events in the Soviet Union, the Government seems to be reacting sensibly. It is advising caution, but not withdrawal from Soviet business; it has suspended, rather than cancelled, the aid it was proposing to give.The good sense of this reaction is particularly welcome as it follows years in which UK trade relations with the Soviets have often appeared to lack basic commonsense. For a long time, Soviet deals were actively discouraged, and those who took the plunge found themselves hamstrung by convoluted rules about what technologies and what services could, and could not, be sold.Then the pendulum swung the other way. The Soviet Union and the whole of eastern Europe appeared to be the lands of opportunity, and companies were positively encouraged to get involved or risk missing out. The trouble with this approach was that it ignored the Soviet Union's inability to pay for its ambitious ideas.Now caution is being advised, with good reason. And that caution is likely to remain the sensible policy no matter what the outcome of this week's startling events.