Moody's, the international ratings agency, said Thursday it had put Japan's sovereign credit rating under review for possible downgrade. Japan's yen debt is currently rated Aa2 by Moody's, having last been downgraded in September 2000. Moody's said the decision to put Japan on review was not a judgement on Prime Minister Junichiro Koizumi's reforms. However, they added that further worsening of the economy may force Koizumi to rethink fiscal reforms. The review process normally takes up to three months.