AMONG the many points of tension between the United States and China, perhaps the single greatest one concerns exchange rates. For more than a decade, Beijing has kept the value of the renminbi, also known as the yuan, more or less constant to the dollar, a strategy that critics say increases the price of American exports to China and fuels the rapidly growing trade deficit with Beijing.

Despite its decision to let the yuan rise 21 percent against the dollar between 2005 and 2008, China has remained a favorite target of Congress. Democrats and Republicans have consistently called for punitive action against China, including sanctions on imports, unless it completely de-links the two currencies.

Lost in the noise, however, is the question of whether de-linkage would actually have any effect on the trade deficit. On this, the United States' 40-year history of pressuring Japan to let the yen appreciate against the dollar is instructive. It indicates that de-linking the yuan would make barely a dent in America's trade deficit. Luckily, this history also points to a different, more effective way for the United States to benefit from China's economic growth.

The Japanese story began in August 1971 when, with the American economy under strong inflationary pressure, President Richard Nixon took the dollar off the gold standard, letting its value fall.

At the same time, with our trade and current-account balances going from surplus to deficit because of rapid export growth in Germany and Japan, President Nixon began pushing the other industrialized countries to allow their currencies to appreciate. With Japan - whose yen was fixed at 360 to the dollar - Nixon played hardball, temporarily imposing a 10-percent surcharge on imports and banning soybean exports to the country.

The strategy worked. That December Japan and nine other countries agreed to let their currencies fluctuate against the dollar within a narrow range of exchange rates. The yen shot up to 315 by the end of the month.

Still our trade deficit with Japan continued to grow. At the end of 1970 it stood at $1.2 billion; by the end of 1972, with the yen at 302 to the dollar, it was $4.1 billion.

Thanks to changes in the global economy, the multilateral currency agreement soon failed, and this allowed the value of the yen to continue rising. By 2006 it stood at 119 to the dollar - more than three times as expensive as in 1971 - and yet the deficit hit an all-time high of $90 billion.

What happened?