Agra, Oct 19 U.S. Ambassador to India Timothy Roemer said here on Monday that strategic and defence co-operation between India and US holds the key to regional security.

"A strong strategic relationship between the United States and India is crucial to address the regional security and challenges such as maintaining peace, security, stability and responding to humanitarian crisis and natural disaster when they occur. Strategic and defence co-operation is one of the key pillars of our growing strategic partnership," said Roemer.

Roemer was in Agra where the U.S. and Indian Air Forces are undergoing an aerial joint exercise session that also focuses on humanitarian assistance and disaster relief missions.

Called 'Exercise Cope India', the joint exercise began on October 15 and will conclude on October 24 at Air Force Station Agra.

During the session, Indian and American air force officials will exchange airlift, air land and airdrop delivery techniques besides participating in aero-medical and disaster management exercises and other flight operations.

Over 150 US airmen, along with three C-130H Hercules, one C-17 Globemaster III, and one C-130J, will join Indian Air Force airmen for the exercise. By Shashank Shantanu(ANI)