United States Vice-President Joe Biden, who is visiting China, has said the US would never default on its debt.In a speech on the last day of his visit, he reiterated that China's large holdings of dollar assets were safe.
His trip comes amid mounting tension between the two over America's debt.
Chinese officials have criticised the political row in the US over raising its borrowing ceiling, and expressed concern over the recent downgrade of the country's credit rating.
"You're safe," Mr Biden told university students in the south-western town of Chengdua, in answer to a question about Washington's ability to repay its debt.
China is the American government's biggest foreign creditor - holding $1tn (£608bn) of US debt - and has called on the country to do more to reduce its budget deficit.
Earlier this month, the US suffered a historic credit downgrade by rating agency Standard & Poor's.
Analysts say China is clearly worried about its holding, and about criticism at home for having so much of the country's savings in US investments. Read BBC Report
All we can in response is Never say Never! The very fact that the #2 man in the US has to reassure the Chinese that Default, which is clearly happening already through inflation, will NEVER happen probably means that it will happen sooner rather than later.