Veteran diplomat and former Foreign Secretary Shivshankar Menon today took over as National Security Adviser. 60-year-old Menon, who will serve in the rank of Minister of State till further orders, took charge from M K Narayanan, who has been appointed as West Bengal Governor.The 1972-batch IFS officer, who retired as Foreign Secretary in July last year, brings with him vast experience in diplomacy.<br/><br/>A highlight of his diplomatic career was the key role he played in negotiations for the landmark Indo-US civil nuclear deal that ended India's long isolation in the atomic sector.<br/><br/>After being named as the NSA on Thursday, Mr.Menon said he is very conscious that it is a big responsibility and he will do his best. Earlier this morning, Prime Minister Dr. Manmohan Singh hosted a farewell lunch for Narayanan, where Finance Minister Pranab Mukherjee, Home Minister P Chidambaram, Defence Minister A K Antony and MoS in PMO Prithviraj Chavan were present.