LONDON — Japan's trade sanctions joust with China is small beer in world terms — or even in the context of the overall commerce between the two nations. But it sounds a warning bell — all the more so since it is just one of a series of challenges to free and open trade that could throw into doubt the attempt to restart the liberalization process brought to a halt by the breakdown of the Seattle conference of the World Trade Organization at the end of 1999.

Most major governments around the world express their support for free trade. Last month, U.S. President George Bush and the leaders of the European Union committed themselves to backing a new trade round when the WTO holds its summit in November.

Given the huge expansion in international commerce since 1945 and the increased prosperity that has accompanied it, this verbal support is hardly surprising. But if one stops for a moment to look at what is actually happening, the picture is a good deal more opaque.

In Europe and the Americas — and on the horizon in East Asia, too — huge economic blocks are taking the place of individual nations, and the result has been to reduce the scope of a truly multinational approach. That has been reinforced by the explosion of bilateral preferential agreements that result in a patchwork of international accords rather than an open playing field for all.

Within that patchwork, the United States and the EU are locked in several big disputes, despite having settled their long-running conflict over banana exports. Europe has banned hormone-treated U.S. beef, provoking tit-for-tat American sanctions on some of its choicer food exports while the Bush administration is, separately, gearing up to cut down steel imports to protect its domestic industry. Potentially more seriously, the EU and the U.S. are at loggerheads over America's Foreign Sales Corporation tax law that Europe regards as a subsidy for exporters.

The EU has won an interim WTO ruling against the FSC, which lets companies claim exemption for some profits earned abroad by putting the sales through offshore subsidiaries. Having rewritten the law — in ways that the EU says are only cosmetic — Washington shows no sign of complying with the ruling. The shocked reaction in the U.S. to the veto of the merger of General Electric and Honeywell by the European Commission is only the freshest indicator of American unwillingness to bow to what Washington sees as uncalled for meddling in its affairs.

Faced with the improbability of a change of heart on FSC, Brussels is talking of imposing $4 billion of sanctions on American exports. Robert Zoellick, the chief U.S. trade negotiator, says that would be like using a "nuclear weapon" on world trade, and there are now suggestions that Washington could react by tabling a complaint of its own with the WTO against European tax breaks for exporters.

On the other side of the globe, the tiff between Japan and China is symptomatic of growing concern about the competitive challenge from China as it engages more deeply with the international economy. This fear is not confined to East Asia. The drawn-out negotiations for Beijing to join the WTO now face objections from a raft of countries that argue China has got too good a deal, and Chinese officials expect a stream of antidumping cases against their exports after their country joins the WTO.

Alongside such particular disputes, the world's agriculture remains highly protected, and governments facing a round of elections in the coming year are not going to risk alienating the farm vote — be it in France, Japan or the American Midwest ahead of next year's congressional elections. As it is, Bush has quite enough of a political test on two fronts.

Congress is dragging its feet on granting him fast-track authorization to sign trade agreements without seeing them bogged down in horse-trading on Capitol Hill. At the same time, the proposed 34-nation Free Trade Area of the Americas is running into party warfare in Washington, with Democrats saying any accord must include environmental and labor protection while the Republican leader in the House of Representatives, Dick Armey, insists that "trade is too important to be compromised by ideology."

The growth in world trade is already forecast to halve this year and next from the high level reached in 2000. At a time of slowing economic growth, the temptation for politicians will be to lean toward protectionism, or, at least, not to push for greater liberalization.

That would be both shortsighted and dangerous. The benefits of liberalization are not only economic. A recent study by the Center for Strategic and International Studies in Washington produced strong evidence that increased openness to commerce helped both environmental protection and labor standards — two particular concerns of the antiglobalization protestors who plan to keep up their pattern of demonstrations when the G8 leaders meet in Italy later this month.

The dangers of erecting barriers to try to protect national economies from an international downturn were amply shown in the 1930s when protectionism exacerbated the slump that began in 1929. Campaigning on a platform of saving jobs by stopping imports may have its attractions for politicians in hard times, but beggar-thy-neighbor policies should be resisted as government leaders make sure that they turn their rhetoric about free trade into concrete measures when the World Trade Organization gets down to picking up the pieces from Seattle.