Helicpoters were pressed into service, while snipers kept a vigil from rooftops.
Armed personnel were present across the capital as part of the annual ground-to-air security arrangement.
The parade was preceded by Prime Minister Singh, Defence Minister A.K.Antony and the service chiefs paying homage at the Amar Jawan Jyoti, an eternal flame in the memory of martyrs who have laid down their lives while defending the nation.
The parade commenced after the customary 21-gun salute and the unfurling of the tricolour, and President Patil presenting the Ashok Chakra, the highest peacetime gallantry award, posthumously to Lieutenant Navdeep Singh who died while foiling an infiltration attempt by four Pakistan-based terrorists along the LoC in Jammu and Kashmir last August.
Image: Subedar Major, Honorary Lieutenant(retd) Joginder Singh receives Ashok Chakra (posthumously) from President Pratibha Patil on behalf of his son Lt. Navdeep Singh during the 63rd Republic Day parade in New Delhi on Thursday, January 26, 2012.