Addressing top commanders of the army, air force and navy in New Delhi, he said India's security challenges remain "diverse and serious" in the form of cross-border terrorism, transnational crime and drug trafficking.
"Added to these are new challenges in areas that constitute the 'global commons' -- such as space, the high seas and cyber space," he said.
Dr Singh also talked about the need to protect "new found equities" like securing the sealanes for energy security.
Underlining that "comprehensive responses" are required to meet "growing complexities", the PM said, "We should aim to abandon single service or segmented approaches and develop synergies across services. Compartmentalised views will only delay our response and dilute its impact."
He particularly stressed the need for increasing capabilities in "emerging areas like cyber and space, which can be the sources of new threats" and said, "We must therefore reorient our mindsets and define a long-term integrated perspective that aligns these capabilities with envisaged outcomes."
Noting that security will remain a "pre-eminent and key pillar" of national strength, the PM said the services will have to equip themselves to meet the evolving challenges.