WASHINGTON (Kyodo) The United States will work aggressively to reopen the Japanese beef market after the import ban was reimposed last week, President George W. Bush said Monday, expressing hope the trade problem will be resolved quickly.

"The problem we've recently had reflects what is necessary to make sure that trade works," Bush said in commenting for the first time over the ban, which was lifted only last month but reinstated after a shipment of U.S. beef was found to contain spinal cord material -- prohibited parts considered a mad cow disease risk.

The shipment arrived Friday at Narita airport.