Addressing a seminar on the occasion of the golden jubilee of National Defence College here, Singh also said that Naxalism and Left wing extremism posed the greatest threats to national security and the state cannot and will not allow its authority to be challenged.

"We have to be prepared to deal with threats to our security from non-state actors and groups... Non-state actors are becoming increasingly fused and employing the best technologies to target open and democratic societies like ours," he said.

Singh did not touch the 26/11 terror strike in Mumbai carried out by Pakistan-based militants but referred to the problem of piracy off the coast of Somalia in the Gulf of Aden as a case in point of the threats to security from non-state actors and groups.

Noting that India has been a victim of terrorism for the past more than two decades, Singh said terrorist groups enjoy patronage and sanctuaries and do not lack in resources.

"We will ensure that our capabilities to combat terrorism remain a step ahead of those of the terrorists. They should be left in no doubt about our ability and resolve to defeat them," he said.