US Assistant Secretary of State for South and Central Asia Robert Blake has describing President Barack Obama's recent India visit as a “watershed” moment in bilateral ties. He told 'The Heritage Foundation', a Washington-based think tank that the two countries have taken concrete initiatives to develop their strategic partnership and are working together to advance global peace and security.He said, the challenge is now to define the agenda for the two governments going forward, capitalise what the two countries have achieved and meet the ambitions vision that Prime Minister Manmohan Singh and Obama laid out.