Over 25,000 police personnel, including those from paramilitary and sharpshooters from NSG, have been already deployed across the city in the run-up to the celebrations, which will be attended by Yingluck Shnawatra, the first woman Prime Minister of Thailand.
To maintain air security, the airspace over the capital will remain closed for an hour tomorrow from 11.15 AM to 12.15 PM.
Snipers were deployed at high-rise buildings while over 160 CCTVs are keeping a tight vigil on people's movement between Rajpath and Red Fort, the route of the parade which showcases India's military might and cultural diversity.
Mobile hit teams, anti-aircraft guns and sharpshooters of the NSG are also on the job at various places while paramilitary and Delhi Police commandos were keeping a close watch along the route of the eight-kilometre long Republic Day parade from Raisana Hills to Red Fort.
A multi-layer security ring has already been put in place at Rajpath, where President Pratibha Patil will unfurl the tricolour and take the salute of marching contingents.
"There is a special emphasis on anti-sabotage checks, access control measures and intelligence coordination. The entire route of the parade will be covered by special security and anti-terror arrangements.
"Elaborate air defence measures, including deployment of anti-aircraft guns, have also been taken to check intrusion of air space," a senior police official said.
Besides the air defence measures, helicopters of the Indian Air Force will hover around Rajpath and all along the route of the parade.
Patrolling in crowded market areas has been intensified and checking and frisking in Metro, railway stations and bus terminals tightened. Security at the IGI airport has also been strengthened in coordination with the CISF.
Checking and frisking have also been intensified at all entry points with police setting up barricades to keep a vigil on all those entering the capital.
No vehicles will be allowed to ply on the Rajpath from 6 PM on January 25 while vehicular movement will be affected on Tilak Marg, Bahadurshah Zafar Marg, Netaji Subhash Marg upto Red Fort from 4 am the next day.