Prime Minister says naxalism is the single largest challenge to internal security and a policy has already been outlined to deal with the menace. Dr. Manmohan Singh rejected the perception that the government underestimated the problem during the first UPA government and made it clear that there is no difference of opinion between the Centre and State governments in dealing with the left-wing extremism. <br/><br/>He was addressing the first national press conference after completion of the one year of the second UPA government at the Centre in New Delhi yesterday.<br/><br/>In response to a question on limited mandate raised by the Home Minister, Dr. Manmohan Singh said that Mr. Chidambaram has already explained the context of his statement. He added that the issue raised by Mr. Chidambaram will be discussed at the Cabinet. He reiterated that Ministers should not air their differences on any issue in public as there are many for available for them to discuss the issues. <br/>