New Delhi will be a sealed fortress on 26 January. Not just on the ground, the security arrangements even in air on Republic Day will be like 'never seen before'.

Security agencies of India are bracing for one of its biggest challenges when US President Barack Obama and Prime Minister Narendra Modi share the dais this Republic Day.

New Delhi will be a sealed fortress on 26 January. Not just on the ground, the security arrangements even in air on Republic Day will be like 'never seen before'.

Here are some of the security arrangements that have been planned for Republic Day:

*Taj Mahal, India Gate shut for public

For the first time in India, the Rajpath and India Gate will remain shut on 26 January. Moreover, the Taj Mahal will also remain closed to the public for the duration of Obama's visit to Agra on 27 January.

* No fly-zone around Rajpath

A no-fly zone around Rajpath and nearby areas will be imposed on 26 January. Apart from the unprecedented ground-to-air security drill during his visit on Republic Day, American authorities had earlier demanded a no-fly zone around Rajpath. After rejecting the demand earlier, Indian authorities gave in on Tuesday. No drones will be used, as had been suggested by American security agencies.

No plane will be be allowed within a radius of 400 kms of the venue of Rajpath as against 300 kms on earlier occasions. This means airports adjoining Delhi like Jaipur, Agra and as far as Lucknow or Amritsar may not operate flights when the function will be on in the national capital.

Sticking to past practice, no plane will land or take off at the Indira Gandhi International Airport during the time when Republic Day will be on at Rajpath.

Earlier, US authorities had demanded a 5-km-radius no-fly zone imposed around Rajpath which would have led to the traditional fly past being cancelled. A request that the Indian military authorities shot down saying that it lasted only for around 10 minutes. Even on Wednesday as Indian officials agreed to a no fly-zone, they made sure the fly past was not cancelled.

*Obama's food, drinking water to undergo 3-layered checking

The food and drinking water to be served to US President Barack Obama and his wife Michelle during their stay at the ITC Maurya will pass through three layers of stingent checking, including by a crack Delhi Police team and the US Secret Service.

While the super-luxury Maurya has its own team of food-testing experts, the food to be served to the US president and his wife will be checked by a Delhi Police team and finally by a team of US Secret Service agents before it is served.

*AWACS to be deployed for vigil from the skies

For the first time, Airborne Warning and Control System (AWACS) are likely to be deployed on the Republic Day for vigil from the skies during the parade where US President Barack Obama will be the Chief Guest.

The AWACS will monitor air space on and around Rajpath where the parade will be witnessed by Obama along with President Pranab Mukherjee, Prime Minister Narendra Modi and a host of other dignitaries. The AWAC detects incoming cruise missiles and aircraft from over 400-km away in all-weather conditions, and direction of air defence fighters besides picking up any low flying object which go undetected by normal radars.

Noting that it will be the first time that AWACS will be deployed for Republic Day, official sources said the step is being taken in view of the heightened threat perception and apprehensions of aerial attack by terrorists.

* Highrise buildings to be shut

Security agencies will partly or completely shut down 71 high rise buildings in the vicinity of Rajpath for this year's Republic Day celebrations, much higher then earlier occasions when only around 45 establishments were closed.

"Earlier, we used to shutdown only around 45 buildings from which Rajpath was directly visible but this time we will occupy 71 buildings which are in close proximity of the parade venue. The new buildings we will dominate this time are mostly high rises from where Rajpath may not be directly visible but from where projectiles can be launched," a senior police official told PTI.

Police will take over these buildings around 1 pm on January 25 and sanitise every nook and corner of these buildings manually. Snipers will be positioned on the roof tops of these buildings after that.

Buildings adjoining the venue, like North and South Blocks, Rail Bhavan, Krishi Bhavan, Shastri Bhavan, Vayu Bhavan, Udyog Bhavan, Nirman Bhavan, Jawahar Bhavan, National Museum and Vigyan Bhavan will be shut by 25 January. Only security personnel will be allowed inside the buildings.

*Sniffer dogs from US to be R-day duty

Around 40 specialist sniffer dogs - Belgian Malinois Shepherd dogs - will be flown down from the US, to double-check the VVIP enclosure at Rajpath (and half-a-dozen other venues Obama will be visiting) is also unprecedented.

Indian agencies' sniffer dogs will also do their duty, but Americans will do their own checks.

*Security forces to work round the clock

The US Secret Service, CIA, Navy Seals and India's Research and Analysis Wing (RAW), Intelligence Bureau, paramilitary forces and Army will be working together round-the-clock to ensure the safety of the two leaders of the two largest democracies who face a high order of threat from global terrorist groups.

*Seven-layer security ring

A seven-layer security ring will be thrown around the VVIP enclosure on Rajpath for the Republic Day parade. The airspace over the area would be monitored by a radar to be specially set up. This will be part of the ground-to-air security drill during Obama visit, which will take him to Agra too. A multi-agency control room will monitor the surveillance operations in every area of the national capital which has been put on the highest alert.

*BSF, which comes under the Home Ministry, has stepped up security along the International Border (IB) in Jammu and Kashmir, deploying close to 1,200 additional personnel there in view of the US President's visit to India.

With inputs from Agencies