Toyota's vehicle-making operations in Japan have been halted since March 14, as the automaker assesses its supply chain.

The automaker told its U.S. employees, plant workers and dealers today that "some production interruptions in North America are likely. It's too early to predict location or duration."

Most of the parts for its North American assembly operations come from some 500 suppliers in the region. "We continue to receive parts from Japan that were already in the pipeline, limiting the immediate impact," Toyota said.

"Dealerships continue to have an ample supply of vehicles, our ships continue to deliver vehicles to North America, and we are doing all we can to ensure our dealers have products available for customers," it said.

Most automakers have halted vehicle output in Japan, and General Motors Co. and others have announced brief stoppages because of supply disruptions.