A day before he demits office, US Ambassador to India Richard Verma, on Thursday underlined how the two countries resolved some "tough issues" during his tenure, including nuclear liability, even as he cautioned against being "complacent".
Terming cross-border terrorism a "serious threat", Mr Verma said it is not for "anyone's lack of effort" that perpetrators of terrorist attacks continue to roam free in Pakistan, whose leaders, he said, have been addressed in "serious terms".
He was speaking at an event at Foreign Correspondents' Club in Delhi in his last public engagement in India in his present capacity.
Asked about the appointments being made by the incoming administration, he said, "As optimistic as I am, I don't want to be complacent. We had to really solve some tough issues in trade, nuclear liability. We've got to keep working at it."
48-year-old Verma, who is of Indian origin, will quit before President-elect Donald Trump assumes charge as his team said the envoys, who are political appointees, will not be given any "grace period" beyond Trump's inauguration day.
Asked about the unfinished trials of 2008 Mumbai terror attacks and the menace of terrorism, Mr Verma said it was a "very vexing" problem and the top-most threat that confronts the US, India and the people of Pakistan.
"It is a scourge that we have to stand up against collectively. No one nation can do it own its own. The challenge of cross border terrorism has been a serious threat and one that we have condemned and addressed in serious terms with leaders in Pakistan.
"We have to continue to work with this. Our security partnership has greatly enhanced, we share more intelligence now. This will require all elements of our national power including countering extremist messages. It's not for a lack of effort on anyone's part," he said.
Mr Verma said the dominant view in Washington was that Indo-US ties were a "non-partisan" endeavour, which he said was on a upward trajectory.
"We are joined together by deep shared values. I have a lot of reason to be optimistic. We have demonstrated to the people that this a relationship that really does help people," he said, hoping the new President would take it forward.
Touching upon the concerns expressed by many on "erosion" of diversity in US, Verma narrated the experiences of his own family, especially his mother, and affirmed "that is the American dream I will continue to cherish, celebrate and protect."
"We have confronted such doubts and headwinds in the past...and the American ideals upon which our country was founded have always prevailed - they will do so again. It will require a resolve, and a commitment to speak up for those who may need a helping hand," he said.
Mr Verma, who had assumed charge as the 25th US Ambassador to India in January 2015, had played a key role in the Congressional passage of the civil nuclear deal and is a strong advocate of closer ties between the two countries.
He had succeeded Nancy Powell, who resigned in March 2014 in the backdrop of a diplomatic row over the treatment meted out to Indian diplomat Devyani Khobragade in the US.