The government said all nuclear installations are absolutely secure. The Minister of State in the Prime Minister's office Mr. Prithviraj Chavan said that there are multiple levels of security. His remarks came in the wake of reports that Centre has asked the state governments having nuclear installations to tighten security around such facilities to foil any possible terror attack. The alert came on the basis of reports that David Headley, a US citizen arrested by FBI on terror charges, had visited these places. Headley, accused of plotting terror attacks in India on behalf of Pakistan-based LeT, had visited Gujarat, Maharashtra and Uttar Pradesh all having crucial nuclear installations raising suspicion that nuclear facilities could be on the radar of the terrorists.