"I don't want to stop the building of new nuclear power plants, but I think we've got to quietly, quickly put the brakes on until we can absorb what has happened in Japan as a result of the earthquake and the tsunami and then see what more, if anything, we can demand of the new power plants that are coming on line," Lieberman said on CBS's "Face the Nation."
"The reality is that we're watching something unfold and we don't know where it's going with regard to the nuclear power plants in Japan right now," Lieberman added.
Japanese authorities were rushing Sunday to prevent at least three nuclear reactors from melting down following Friday's 8.9-magnitude deadly earthquake and subsequent tsunami.
Lieberman said he believes there is only a "remote" risk that radiation from the Japan plants could leak into the atmosphere and reach the United States.
Lieberman added that he talked earlier Sunday with Federal Emergency Management Agency chief Craig Fugate. According to Lieberman, Fugate said the U.S. government is ready to respond to a catastrophe involving one of the 104 nuclear power plants in the United States. But Fugate told Lieberman his concern is that individuals are not ready for such a disaster.
"What this horrific natural disaster in Japan has to do for all of us is to go back and look at our preparedness for such a catastrophe here," Lieberman said.
Fugate is expected to testify this week before Lieberman's panel.