On the margins of a summit meant as a show of force for a Russian leader seeking a turnaround on the battlefield, Prime Minister Narendra Modi of India leaned in with a different message.

"Democracy, diplomacy and dialogue” — not war — is the answer, he told Russian President Vladimir Putin as the cameras rolled on Sept. 16, before declaring that the two would speak more about how to bring peace in Ukraine.

That assured interaction in Uzbekistan was the latest display of India’s rise under Modi. An ambitious and assertive power, India has become increasingly indispensable in the search for answers to some of the world’s most pressing challenges, from diplomacy to climate change to technology and trade to efforts at diversifying supply chains to counter China.