SCHOFIELD BARRACKS — Forty Indian soldiers in jungle camouflage descend on a mock village in the central O'ahu mountains, hunting for insurgents. American officers watch for lessons they can apply when leading their own soldiers through the same course on a U.S. Army training ground.

The troops are on the island for the biggest joint drills the Indian and U.S. armies have had to date, the latest sign of growing military relations between the two nuclear powers.

The bilateral exercise, called Yudh Abhyas, or "training for war" in Hindi, started four years ago with a handful of Indian and U.S. soldiers. It has since ballooned to feature hundreds of troops, including 140 Indians who flew to Hawai'i, which hosts the U.S. Pacific Command, whose reach extends to their homeland.

"It's a tremendous expansion," said Col. Dinesh Singh, of the Indian army's 3rd Battalion, 9th Gurkha Rifles. He added the exercises were now teaching platoons from the two nations how to talk to each other in the field, moving beyond the basics of training individual soldiers.

The U.S.-Indian military relationship is relatively young, with the two sides having had little interaction during the Cold War, when socialist India was closer to the Soviet Union. They found more common ground in the 1990s, a trend that accelerated after the Sept. 11, 2001, terrorist attacks, which led the United State to seek India as a partner in the war against terror.

Analysts say the United States is eager to deepen military ties with India to learn some of the counterinsurgency methods India's military has cultivated during its long battle against separatists in Kashmir. The Americans also want India's large navy to help patrol the seas for terrorists and pirates, analysts say.

There's also a U.S. desire to use India to balance China's growing power and influence, said Itty Abraham, research fellow with the Washington, D.C., office of Hawai'i's East-West Center.

"From the government's point of view, India has become, though people in Washington won't admit it so openly — it's not a nice thing to say — America's counterweight to China," said Abraham.

India, meanwhile, is eager to learn from the world's most technologically advanced military.

Donald L. Berlin, a professor at the Asia-Pacific Center for Security Studies in Honolulu, said India also believes a closer relationship with the United States will help it become a bigger power in the Indian Ocean, in South Asia, and in the world.

The friendship has its obstacles, of course.

The U.S. Congress hasn't approved an agreement signed by the two nation's leaders in March that allows U.S. civil nuclear trade with India in return for safeguards and inspections at India's 14 civilian nuclear plants.

Supporters say the deal strengthens a strategic relationship with a friendly country that has long maintained a responsible nuclear program. Plus it would provide clean energy to a country desperate to fuel a booming economy.

Critics counter that the plan encourages the spread of nuclear weapons and fans an India-Pakistan nuclear arms race by effectively giving U.S. recognition to India's nuclear weapons program. They also complain the agreement doesn't allow for inspections at India's eight military plants.

Such concerns were remote at Schofield Barracks, however.

Maj. Bob Risdon, who designed the exercises for the U.S. Army's 1st Battalion, 21st Infantry Regiment, said U.S. troops could learn from how Indian forces requested homeowners to lead them on searches of their homes. They were less intrusive in searching people's homes and cars, a tactic that could help when troops are trying to earn the trust of the local population, he said.

"You can figure out a lot about people that way, too. You can figure out if they're trying to hide something," Risdon said.

Lt. Col. Matt Kelley, the 1st Battalion commander, said the way Indians ambushed and disarmed two insurgents impressed him. American troops, in the same drill, simply shot and killed the men, he said.

"They've just gained huge intelligence value from that — instead of killing them, they've captured them," Kelley said. "All our guys said whoa — we'd never do that. We could do it."

Singh, the Indian army commander, said he valued the heightened reality of the U.S. designed exercises, which forced troops to react quickly and rely on their reflexes.

"India is the world's largest democracy. They're a strategic partner for the United States and an important friend for the United States," said Col. Mark Haskins, the U.S. Pacific Command's South Asia policy chief.