"There are a number of things in motion right now, and decisions will be coming very soon," Mattis told members of House Armed Services during a Congressional hearing on Afghanistan.
"We're both working to turn these big words into pragmatic realities and because I see both sides working together on it. I'm optimistic," he said, adding that India-US political relationship can be tightened together.
"They (India) are a force for stability in South Asia. They're a force for stability in the Indo-Pacific region. They're a nation coming into their own, economically, as a great nation, as they have steady growth rates going on right now," he added.
"There's an opportunity here that we have not experienced in decades to tie us together in terms of broadened level of cooperation and a natural alignment with each other's interests," he said.
Responding to another question, Mattis said India has an "outsized role" to play in the region because of its size.
"It's as raucous a democracy as we are, frankly. It gives people hope that their voices can be heard and economic opportunity can be passed broadly in a society, not to a corrupt few. I think their example alone is important. It's why we are looking at this strategic convergence as an opportunity for steady engagement, so we have to do pragmatic things together," he said.