But on Wednesday the British government, showing the kind of clear thinking that has been all too scarce on this side of the pond, announced a plan to provide banks with £50 billion in new capital  the equivalent, relative to the size of the economy, of a $500 billion program here  together with extensive guarantees for financial transactions between banks. And U.S. Treasury officials now say that they plan to do something similar, using the authority they didn’t want but Congress gave them anyway.

The question now is whether these moves are too little, too late. I don’t think so, but it will be very alarming if this weekend rolls by without a credible announcement of a new financial rescue plan, involving not just the United States but all the major players.

Why do we need international cooperation? Because we have a globalized financial system in which a crisis that began with a bubble in Florida condos and California McMansions has caused monetary catastrophe in Iceland. We’re all in this together, and need a shared solution.

Why this weekend? Because there happen to be two big meetings taking place in Washington: a meeting of top financial officials from the major advanced nations on Friday, then the annual International Monetary Fund/World Bank meeting Saturday and Sunday. If these meetings end without at least an agreement in principle on a global rescue plan  if everyone goes home with nothing more than vague assertions that they intend to stay on top of the situation  a golden opportunity will have been missed, and the downward spiral could easily get even worse.

What should be done? The United States and Europe should just say “Yes, prime minister.” The British plan isn’t perfect, but there’s widespread agreement among economists that it offers by far the best available template for a broader rescue effort.

And the time to act is now. You may think that things can’t get any worse  but they can, and if nothing is done in the next few days, they will.