National security strategy, military and equipment modernisation, defence reform besides garnering more funds for the ministry are the areas of challenge for the new Defence Minister Rajnath Singh, according to analysts here.Defence experts are also of the view that the helicopter fleet of all three services require extensive replacement.Singh, on Saturday, took charge as the country's Defence Minister. He is the fourth face to head the ministry in five years after Arun Jaitely (who had two stints), Manohar Parrikar and Nirmala Sitharaman.He was received by Minister of State for Defence Shripad Yesso Naik who took charge on Friday, as well as by Army Chief General Bipin Rawat, Air Force Chief Air Chief Marshal B.S. Dhanoa and Navy Chief Karambir Singh."The main challenge for Rajnath Singh is the preparation of a National Security strategy which was to be prepared by the newly constituted Defence Planning Committee. This will provide new guidelines to the services to prepare strategies," former Brigadier and defence expert S.K. Chatterjee told IANS."The country also has to decide on the induction of S-400 defence systems of the Russians keeping in view its impact on our relationship with the Americans," he said.The analysts felt that with the government giving more emphasis to the Make in India initiative, the focus should now be on production rather than on buying hardware."Defence production with other countries need to be sorted out. We should enter into production with Russia, America, Israel and other countries," defence expert Qamar Agha said.According to the experts, for Singh, who has been a successful Home Minister, the road ahead won't be that tough as he is a team leader and will take along all the three services.Chatterjee said that the military and equipment modernisation is in progress currently, following a rather slow decade in this regard. The requirement is to push the pace in major areas of concern, including on air power resources, he added.The experts were also of the opinion that the Assam Rifles should continue under the Army's operational control, otherwise it would lead to a steep decline in their combat capability.Earlier in the day, the new Defence Minister visited the National War Memorial and paid homage to the martyrs.