For once deflation has taken hold, monetary policy becomes a blunt tool.

ECONOMIST: Euro-area economies

But unsterilised intervention is only monetary policy by another name, not an extra policy tool.

ECONOMIST: Meddling in the currency market

Because Europe's governments have signed away national control of interest rates, fiscal policy is the only tool to hand if the single monetary policy leaves their economies growing more slowly than they might, or faster than they can sustain without pressure on wages and property prices.

ECONOMIST: Europe grows apart

In short, monetary policy should not be an economic tool for heating or cooling economic activity.

FORBES: Slick Solution

Under those conditions, looser monetary policy could also be a useful tool.

ECONOMIST: In due course it will stop. Until then, one stands in awe

Mr. BERNANKE: But for right now, my focus obviously is on monetary policy, which is the immediate tool that we have to try to address the risk that our economy faces.

NPR: Bernanke Hints at Further Interest Rate Cuts

Blanchard says the only tool that remains is monetary policy -- a cut to interest rates.

CNN: Fast, medium or slow: Which economic speed is your country?