To understand this concept, start with the actual unemployment equal to the NAIRU. Then, assume that a country's government and its central bank use demand-side policy to reduce the unemployment rate and then attempt to keep the rate at a specific low level: rising budget deficits or falling interest rates increase aggregate demand and raise employment of labor. Thus, the actual unemployment rate falls, as going from point A to B in the nearby graph. Unemployment then stays below the NAIRU for years or more, as at point B. In this situation, the theory behind the NAIRU posits that inflation will accelerate, i.e. get worse and worse (in the absence of wage and price controls). As the short-run Phillips curve theory indicates, higher inflation rate results from low unemployment. That is, in terms of the "trade-off" theory, low unemployment can be "bought," paid for by suffering from higher inflation. But the NAIRU theory says that this is not the whole story, so that the trade-off breaks down: a persistently higher inflation rate is eventually incorporated as higher "inflationary expectations". Then, if workers and employers expect higher inflation, it results in higher inflation, as higher money wages are passed on to consumers as higher prices. This causes the short run Phillips curve to shift to the right and upward, worsening the trade-off between inflation and unemployment. At a given unemployment rate, inflation accelerates. But if the unemployment rate rises to equal the NAIRU, we see higher inflation than before the expansionary policies, as at point C in the nearby diagram. The fall of the unemployment rate was temporary because it could not be sustained. In sum, the trade-off between inflation and unemployment cannot be relied upon to be stable: taking advantage of it causes it to disappear. This story fits the experience of the United States during the late 1960s, during which unemployment rates stayed low (below 4% of the civilian labor force) and inflation rates rose significantly.