The United States and India will seek to finalise a number of defence agreements during high-level talks this week that aim to draw their two militaries closer and counter-balance China's influence in the region.
US Defence Secretary Jim Mattis and Secretary of State Mike Pompeo will hold talks with India's Foreign Minister Sushma Swaraj and Defence Minister Nirmala Sitharaman for the so-called two-plus-two discussions.
Already cancelled twice this year, it is the highest level of dialogue between the two countries and was agreed upon by US President Donald Trump and Indian Prime Minister Narendra Modi last year.
Officials and experts believe that the meeting is not only symbolically important, but will give the world's two largest democracies a chance to make concrete progress while ironing out significant differences, including over India's ties with Russia and Iran.
"The 2+2 presents an historic opportunity to develop our growing partnership and to explore ways of enhancing our security cooperation," the top US military officer, Marine General Joseph Dunford, told reporters travelling with him to the talks.
The talks will be held on Thursday.
Randall Schriver, the Pentagon's top Asia official, predicted last week that the discussions would produce "a set of actual concrete outcomes."
The United States and India have increased defence ties over the past decade, in part because of mutual concerns over an increasingly assertive China.
India has been alarmed at China's expanding security and economic links in South Asia. The nuclear-armed Asian giants were locked in a 10-week military stand-off last year in a remote, high-altitude stretch of a boundary in the Himalayas.
Earlier this year, the US military renamed its Pacific Command the US Indo-Pacific Command, a move underscoring the growing importance of India to the Pentagon.
Among the topics for discussion, the United States is hoping to finalize an agreement on a communications framework that would allow for securely sharing information.
The Communications Compatibility and Security Agreement (COMCASA) has long been a demand of the United States and would open the door for Washington to sell sensitive defence equipment to India, like the armed version of Guardian drones.
India has historically been opposed to the agreement because it sees it as being too intrusive. Earlier this year however, an Indian defence source told Reuters that New Delhi had shed its opposition to the agreement.
"That would be a big deal, if that announcement comes out of this... in terms of advancing the interoperability, that would really be a kind of big next step," said Alyssa Ayres, a former US State Department official and now a senior fellow at the Council on Foreign Relations.
The two sides are also negotiating another agreement, a Basic Exchange and Cooperation Agreement (BECA), which would enable them to share advanced satellite data for navigation and missile targeting, Indian military sources said.
The United States is keen to tap into India's large defence market. It has emerged as India's No 2 weapons supplier, closing $15 billion worth of deals over the last decade.
A senior US defence official, speaking on the condition of anonymity, said the two countries were looking at a carrying out a major joint exercise - involving troops on land, at sea and in the air. Further details were not immediately available.
The two countries hold elaborate navy-to-navy manoeuvres, air exercises and even drills involving Special Forces, but war games involving all three arms represent a scaling up of defence cooperation.
