For his part, Sigh told reporters he wanted to see the US and India standing "shoulder-to-shoulder".
"India and the United States must stand tall, stand shoulder-to-shoulder and that's what is going to happen," Singh said.
The meeting on the northern Japanese island of Hokkaido came a day after a bloc of
Indian left-wing parties quit Singh's coalition government in protest over the planned nuclear deal with the US.
The four-party communist-led bloc, which has 59 seats in the 545-member parliament, had provided Singh's government with a parliamentary majority for four years.
The proposed civilian nuclear deal, first put forward more than three years ago, has been widely criticised on both sides.
If it is eventually ratified by Washington and New Delhi, it would reverse three decades of US policy by allowing the sale of nuclear fuel and technology to India, which has not signed international non-proliferation accords but has tested nuclear weapons.
As part of the deal, India, would open its civilian reactors to international inspections.
Indian critics of the plan say the agreement would undermine India's weapons programme and give Washington too much influence over Indian foreign policy.
In the US meanwhile, opponents of the deal say it could spark a nuclear arms race in Asia and weaken international efforts to prevent states like Iran and North Korea from acquiring nuclear weapons.