Prime Minister Dr. Manmohan Singh returned New Delhi last night after a nine-day trip to the US and Trinidad and Tobago during which India and the US decided to transform their ties into one of the defining relationships of the 21st century.<br/><br/>During his four-day State Visit to the US, first by a foreign leader under the 10-month old Obama Administration, Dr. Singh met President Barack Obama at the White House and held talks on the entire gamut of bilateral relations, situation in the region and global challenges like terrorism, climate change and economic crisis.<br/><br/>During the visit, the two sides also signed MoUs in counter-terrorism among others, and both sides decided to chalk out a new path for further bilateral ties. <br/><br/>After his US visit, the Prime Minister left for Port of Spain, the capital of Trinidad and Tobago, to attend the Commonwealth Summit.<br/><br/>Dr. Singh also met French President Nicholas Sarkozy, British PM Gordon Brown and his Canadian counterpart Stephen Harper. A highlight of the visit was the conclusion of negotiations on Civil Nuclear agreement with Canada.<br/><br/>In Port of Spain, where he attended a two-day meeting of the Commonwealth leaders, the Prime minister had pushed for a legally binding substantive outcome at the Copenhagen climate change meet next month.