Illustration by Jon Berkeley

MANAGING a crisis as complex as this one has so far called for nuance and pragmatism rather than stridency and principle. Should governments prop up credit markets by offering guarantees or creating bad banks? Probably both. What package of fiscal stimulus would be most effective? It varies from one country to the next. Should banks be nationalised? Yes, in some circumstances. Only the foolish and the partisan have rejected (or embraced) any solutions categorically.

But the re-emergence of a spectre from the darkest period of modern history argues for a different, indeed strident, response. Economic nationalism—the urge to keep jobs and capital at home—is both turning the economic crisis into a political one and threatening the world with depression. If it is not buried again forthwith, the consequences will be dire.

Devil take the hindmost

Trade encourages specialisation, which brings prosperity; global capital markets, for all their problems, allocate money more efficiently than local ones; economic co-operation encourages confidence and enhances security. Yet despite its obvious benefits, the globalised economy is under threat.

Congress is arguing about a clause in the $800 billion-plus stimulus package that in its most extreme form would press for the use of American materials in public works. Earlier, Tim Geithner, the new treasury secretary, accused China of “manipulating” its currency, prompting snarls from Beijing. Around the world, carmakers have lobbied for support (see article), and some have got it. A host of industries, in countries from India to Ecuador, want help from their governments.

The grip of nationalism is tightest in banking (see article). In France and Britain, politicians pouring taxpayers' money into ailing banks are demanding that the cash be lent at home. Since banks are reducing overall lending, that means repatriating cash. Regulators are thinking nationally too. Switzerland now favours domestic loans by ignoring them in one measure of the capital its banks need to hold; foreign loans count in full.

Governments protect goods and capital largely in order to protect jobs. Around the world, workers are demanding help from the state with increasing panic. British strikers, quoting Gordon Brown's ill-chosen words back at him, are demanding that he provide “British jobs for British workers” (see article). In France more than 1m people stayed away from work on January 29th, marching for jobs and wages. In Greece police used tear gas to control farmers calling for even more subsidies.

Three arguments are raised in defence of economic nationalism: that it is justified commercially; that it is justified politically; and that it won't get very far. On the first point, some damaged banks may feel safer retreating to their home markets, where they understand the risks and benefit from scale; but that is a trend which governments should seek to counteract, not to encourage. On the second point, it is reasonable for politicians to want to spend taxpayers' money at home—so long as the costs of doing so are not unacceptably high.

In this case, however, the costs could be enormous. For the third argument—that protectionism will not get very far—is dangerously complacent. True, everybody sensible scoffs at Reed Smoot and Willis Hawley, the lawmakers who in 1930 exacerbated the Depression by raising American tariffs. But reasonable people opposed them at the time, and failed to stop them: 1,028 economists petitioned against their bill. Certainly, global supply-chains are more complex and harder to pick apart than in those days. But when nationalism is on the march, even commercial logic gets trampled underfoot.

The links that bind countries' economies together are under strain. World trade may well shrink this year for the first time since 1982. Net private-sector capital flows to the emerging markets are likely to fall to $165 billion, from a peak of $929 billion in 2007. Even if there were no policies to undermine it, globalisation is suffering its biggest reversal in the modern era.

Politicians know that, with support for open markets low and falling, they must be seen to do something; and policies designed to put something right at home can inadvertently eat away at the global system. An attempt to prop up Ireland's banks last year sucked deposits out of Britain's. American plans to monitor domestic bank lending month by month will encourage lending at home rather than abroad. As countries try to save themselves they endanger each other.

The big question is what America will do. At some moments in this crisis it has shown the way—by agreeing to supply dollars to countries that needed them, and by guaranteeing the contracts of European banks when it rescued a big insurer. But the “Buy American” provisions in the stimulus bill are alarmingly nationalistic. They would not even boost American employment in the short run, because—just as with Smoot-Hawley—the inevitable retaliation would destroy more jobs at exporting firms. And the political consequences would be far worse than the economic ones. They would send a disastrous signal to the rest of the world: the champion of open markets is going it alone.

A time to act

Barack Obama says that he doesn't like “Buy American” (and the provisions have been softened in the Senate's version of the stimulus plan). That's good—but not enough. Mr Obama should veto the entire package unless they are removed. And he must go further, by championing three principles.

The first principle is co-ordination—especially in rescue packages, like the one that helped the rich world's banks last year. Countries' stimulus plans should be built around common principles, even if they differ in the details. Co-ordination is good economics, as well as good politics: combined plans are also more economically potent than national ones.

The second principle is forbearance. Each nation's stimulus plan should embrace open markets, even if some foreigners will benefit. Similarly, financial regulators should leave the re-regulation of cross-border banking until later, at an international level, rather than beggaring their neighbours by grabbing scarce capital, setting targets for domestic lending and drawing up rules with long-term consequences now.

The third principle is multilateralism. The IMF and the development banks should help to meet emerging markets' shortfall in capital. They need the structure and the resources to do so. The World Trade Organisation can help to shore up the trading system if its members pledge to complete the Doha round of trade talks and make good on their promise at last year's G20 meeting to put aside the arsenal of trade sanctions.

When economic conflict seems more likely than ever, what can persuade countries to give up their trade weapons? American leadership is the only chance. The international economic system depends upon a guarantor, prepared to back it during crises. In the 19th century Britain played that part. Nobody did between the wars, and the consequences were disastrous. Partly because of that mistake, America bravely sponsored a new economic order after the second world war.

Once again, the task of saving the world economy falls to America. Mr Obama must show that he is ready for it. If he is, he should kill any “Buy American” provisions. If he isn't, America and the rest of the world are in deep trouble.