The pace of economic growth has increased in the United States.
Figures issued by the Commerce Department on Friday showed gross domestic product expanded at an annualised rate of 2.8% in the final three months of 2011, its fastest rate in more than a year.
Analysts say the main contribution came from firms stockpiling goods they had produced, rather than selling them, and that won't continue in this quarter, resulting in lower growth.
Treasury Secretary Timothy Geitner says the US economy is sensitive to what happens abroad, as well as at home.
''It's going to take a long time, still, for us to fully repair the damage, particularly unemployment," he told CNN from the World Economic Forum in Davos, Switzerland.
"Unemployment is still very high. Housing is still very, very weak. Construction is very weak. People still have too much debt," Mr Geithner said.