Ahead of US President Barack Obama's visit, an intense security drill involving US secret service agents, Indian intelligence agencies and NSG commandos will take place in Mumbai today. A similar exercise will also be carried out in Delhi tomorrow to fine-tune the security arrangements in the national capital during Obama's visit. On a three-day visit to India, the US President will arrive in Mumbai on 6th November and in Delhi a day after. All high-rise buildings in the vicinity of Mumbai's Taj Mahal hotel and Delhi's Maurya Sheraton hotel, where the US President will stay, will be sanitised and security personnel will guard them from rooftop to prevent any air-borne attack. The Mumbai coastline will be guarded by Indian Navy personnel while the skies of both the cities will be protected by IAF fighter jets and helicopters. The Ridge area — opposite Delhi's Maurya Sheraton hotel — has been illuminated by floodlights as part of the heightened security drill. The Home Ministry has already issued an alert for Mumbai and Delhi asking authorities to take extra precautions during Obama's visit as well as on Diwali on Friday.