The Japanese government acknowledged Friday that it was overwhelmed by the scale of last week's twin natural disasters, slowing the response to the nuclear crisis that was triggered by the earthquake and tsunami that left at least 10,000 people dead.
The admission came as Japan welcomed U.S. help in stabilizing its overheated, radiation-leaking nuclear complex, and reclassified the rating of the nuclear accident from Level 4 to Level 5 on a seven-level international scale, putting it on a par with the 1979 Three Mile Island accident.
Nuclear experts have been saying for days that Japan was underplaying the crisis' severity.
The International Nuclear Event Scale defines a Level 4 incident as having local consequences and a Level 5 as having wider consequences.
The reclassification did not appear to signal that the crisis had grown more severe, only that officials felt it needed to be upgraded.