On the eve of Independence Day, India on Monday raised security around the country to unprecedented levels alarmed by the big terror attack plot in Britain and a US embassy advisory warning of likely terror strikes in metropolitan cities.
Hundreds of security personnel and policemen fanned out across cities and sites considered to be potential terror targets even as safety measures were reinforced in airports with increased deployment of Central Industrial Security Force (CISF) personnel.
Across the country, crack anti-terrorist commandos were positioned at vital installations like nuclear plants, national monuments and airports forcing heightened vigil.
Snipers, metal detectors, X-ray machines, sniffer dogs, radio frequency jammers and security cameras were being deployed at crowded market places, shopping malls, airports and government buildings.
Police in over half a dozen states spread across eastern, central and southern India have also increased vigil to prevent attacks by Maoist rebels.
Following last month's bombings, Mumbai has been placed on high alert and a security blanket thrown around key government and private buildings.
The threat was the highest in the Capital as the main celebrations on August 15 are centred at the historic Red Fort where Prime Minister Manmohan Singh will hoist the national flag and address the nation from its ramparts.
The security arrangements in place were mind-boggling. Anti-aircraft guns were located around the fort, snipers positioned on rooftops and high-rise buildings around the fort's vicinity while choppers will criss-cross the skies when Singh addresses the nation.
New Delhi has been declared a no-fly zone for the morning of August 15 and air defence guns have been placed at strategic locations to ward off possible aerial attacks by unmanned or micro light aircraft.
"The area will be completely sealed late Monday evening as 4000 security personnel will guard the fort. All of them will be heavily armed," said a senior security official.
"This is certainly an unusual situation. We are constantly reviewing security arrangements and in all likelihood there will be four levels of security when the Prime Minister addresses the country on Tuesday."
Delhi Police have already unveiled an elaborate list of dos and don'ts for commuters and citizens for August 15, blocking off all vehicular traffic in and around the Red Fort within a radius of three kilometres.
Security has also been beefed up for the Delhi Metro with an additional 3500 personnel deployed at various stations.
Top officials of the home ministry and Intelligence Bureau met on Monday after a full dress rehearsal for the Independence Day celebrations at the Red Fort and decided to deploy more plainclothes personnel in public areas like markets.