In the annals of Indo-US ties, 2015 would be remembered as a transformative year which set the tone for a new dimension of active engagements at the top leadership level and a growing defence partnership that is set to become an anchor of global security.

The year started with a historic India visit of US President Barack Obama where he attended the annual Republic Day Parade in New Delhi on January 26. By this he not only became the first American president to attend the top Indian parade, but also only the first one to visit India twice.

Dismissing the security concerns of the secret service, Obama sat in an open arena for three hours watching the parade that gave him a glimpse of India's cultural diversity and its military might. His visit also resulted in resolving the contentious pending issues in the civil nuclear deal.

President Obama and Prime Minister Narendra Modi decided to establish a hotline between them and launch a Strategic and Commercial Dialogue and renew India-US Defence partnership agreement; thus giving a new dimension to this strategic bilateral ties at a time when China is flexing its muscle in disputed South China Sea.

The results were visible by the time when curtain came down on 2015. Obama and Modi had met thrice during the year - the two subsequent meetings were in New York on the sidelines of the UN General Assembly and one in Paris on the sidelines of the climate change summit.

Obama and Modi started talking frequently over the hotline, after it was established this summer. The US President has hotline or a secure line of communication only for a few world leaders.

US Ambassador to India Richard Verma said that during the recently concluded climate negotiations in Paris President Obama and Prime Minister Modi talked regularly on new secure communications lines to find common ground and develop ways to proceed in reaching an agreement.

"What we are witnessing in the US-India partnership is the culmination of years of effort - actually decades of hard work - that has yielded important results for both nations. This past year, in particular, was especially transformative," he said.

This Fall India and the US launched the first-ever Strategic and Commercial Dialogue, bringing a whole-of- government approach.

Currently there are 30+ working groups and government-to-government dialogues between the two sides that have been established on everything from space cooperation, cyber security, global health security and civil aviation.

In December, Manohar Parrikar became the first Indian defence minister to visit the Pacific Command headquarters in Hawaii and given a rare insight of a nuclear powered aircraft carrier.