LONDON (MarketWatch) -- Reports Wednesday suggested that Chinese officials have begun threatening a concerted series of foreign reserve sales to deliberately weaken the U.S. dollar and punish the U.S. Congress for its efforts to impose trade tariffs.

We should be so lucky.

Such sales would effectively accomplish what China's congressional critics want -- i.e. reduce U.S. imports -- while at the same time destroying part of the value of China's foreign exchange holdings.

Massive sales of U.S. treasuries would doubtless cause interest rates to rise and, combined with the already faltering U.S. housing market, probably push the U.S. economy into a recession we're probably overdue for.

The real question the Chinese leadership must resolve is whether the damage to their own country's economy, or at least to its apparatchiks and nouveau oligarchs, would be any less severe.

In some ways the U.S. relationship to China is a variant of the old saying: If you owe a billion dollars, the bank owns you. If you owe a trillion dollars, you own the bank.

As China's most significant export market, a healthy U.S. economy means China has a place to offload all the plastic gizmos it can make, along with toys covered in lead-based paints and tubes of toxic toothpaste.

Maintaining blistering growth has been important enough for China's own "political" leadership that they've been willing to subsidize U.S. consumption by buying up U.S. debt and keeping interest rates low.

At some point that will have to change. China will have to let its currency's appreciation against the dollar accelerate, irrespective of what anybody in Congress says.

So Americans should probably be grateful. After all, as long as we're heading down this mountain with no brakes on, we're better off having the accident sooner rather than later, even if the collateral damage takes out a few politicians on both sides of the Pacific.

- Tom Bemis