Over the past year, two legal bombshells have put India’s growing ties with the United States to one of its biggest tests yet.

Just as the two sides announced unprecedented expansions in defense and technology ties, US prosecutors accused Indian government agents of is planning an assassination an American citizen on US soil.

Months later, the Ministry of Justice filed charges of fraud and bribery against India’s biggest business mogul, whose businesses have soared to dizzying heights thanks to the power of Prime Minister Narendra Modi.

Nevertheless, the relationship was maintained. After decades of mutual suspicion between the two countries, said Eric Garcetti, the outgoing US ambassador to India, the fact that nothing can now disrupt their ties is a testament to their strength.

“I don’t think there is anything big enough to threaten the trajectory of US-India relations,” Mr. Garcetti in an interview at the embassy in New Delhi on Saturday, two days before President Biden leaves office.

“This is incredibly resilient and almost inevitable,” he added. “It’s just the pace and progress that’s not inevitable, like how quickly we’re getting there.”

The Biden administration’s doubling down on relations with India comes after nearly two decades of efforts to shake off Cold War-era suspicions that culminated in US sanctions on India’s nuclear program in 1998.

Washington sees great potential in India as a geopolitical counterbalance to an increasingly assertive China. Already the world’s largest democracy, India took over from China as the world’s most populous nation in 2023. India’s demographic advantages and growing technological capacity could help diversify global supply chains away from China, a priority for the United States and other major powers.

With Donald J. Trump’s second term as president beginning on Monday, his America First rhetoric and threats of high tariffs have unsettled leaders in many countries. Indian officials insist they are not among them.

S. Jaishankar, the foreign minister, said India had a “positive political relationship with Trump” that he hoped would only deepen. While attending the opening of the US consulate on Friday in the technology hub of Bengaluru, also known as Bangalore, Mr. Jaishankar quoted Mr. Modi who said the two countries were overcoming “historic hesitations”.

Mr. Modi enjoys a strong relationship with Mr. Trump, an important factor due to the future president’s personal approach to international relations. During Mr. Trump’s first term, Mr. Modi hosted him for a large rally in his home state of Gujarat, as well as a large gathering of the Indian diaspora in Texas — an increasingly important extension of Indian influence in American politics.

But some analysts warned that Mr Trump’s unpredictability and transactional approach could pose risks for India.

Two issues in particular will put the relationship to the test, and very likely soon. During the campaign, Mr. Trump criticized India for gaining an unfair advantage in trade by maintaining high tariffs. And India could be embroiled in controversy if Mr. Trump follows through on his promise of mass deportations of illegal immigrants.

Indians make up the third largest group of illegal immigrants in the United States, according to Pew Research Center. If Mr. Trump sends a large number of Indians back to their homeland, it could be a big embarrassment for Mr. Modi.

Amita Batra, a New Delhi-based economist and trade expert, said India should see warning signs in Trump’s threat of higher tariffs even against America’s traditional allies, as well as his expressed willingness to undo deals with countries such as Mexico and Canada that it has made his own first administration.

“You can say we have a great relationship with Trump, we have an easy relationship with the United States, but how Trump views it at a certain point in time is a different question,” Dr Batra said at an event at the Center for Social and Economic Progress in New Delhi. . “India must approach Trump 2.0 very cautiously.”

During the interview, Mr. Garcetti described the bilateral relationship as “the most interesting, the most challenging and the most consequential” for both countries.

The former Democratic mayor of Los Angeles, Mr. Garcetti arrived in New Delhi in April 2023, after the mission had been without an ambassador for two years. His confirmation process hit a wall amid allegations that he overlooked sexual harassment complaints from aides while mayor.

He made up for lost time with a burst of energy and penetration like that of a politician on the campaign trail.

He was everywhere from cricket ground to cafeteria to cultural programs. Wearing a leather jacket, he even sat down at the piano to open for jazz legends Herbie Hancock and Dianne Reeves, who came to perform at the Piano Man Jazz Club in New Delhi.

But by the time Mr. Garcetti tried his hand at dancing to a popular Bollywood tune on the celebration of Diwali, relations between the two countries encountered major obstacles.

In India, right-wing trolls seized on American allegations of the Indian government’s involvement in a conspiracy to kill an American citizen who championed the separatist cause in India. That, along with the US indictment of Gautam Adani, the business mogul, was evidence that the United States was trying to slow India’s inevitable rise, nationalist voices online argued.

The Biden administration appeared intent on handling the assassination episode quietly with New Delhi, demanding accountability without allowing it to become a major diplomatic sore point.

“On Capitol Hill, inside the White House, I think with those who know it was the right moment to think and pause,” said Mr. Garcetti on the assassination case. “It didn’t stop the momentum — you know, relations between countries are always multilateral and simultaneous, not just between governments. But I think it was a momentary gut check.”

Mr. Garcetti said the Biden administration was reassured by India’s response. New Delhi accepted the US demand, he said, “not just for accountability, but for systemic reform and assurances that this will never happen again.”

An Indian government investigation that ended last week recommended legal action against an unnamed person with “past criminal links.” It said the action “must be completed expeditiously,” which analysts saw as an attempt to restart the Trump era.

“If we want to cooperate in other areas that are important to us, intelligence sharing and so on, trust is the basis of everything,” said Mr. Garcetti. “But I was quite taken with how trust can be deepened through challenge.”

One question hovering over the deepening ties between the two countries is whether India can truly emerge as an alternative to China in global supply chains – something Mr. Garcetti also asked.

India has only reaped a fair share of the windfall from the move out of China, with companies preferring places like Vietnam, Taiwan and Mexico, where it’s easier to do business and where tariffs are lower.

Mr. Garcetti said India made dramatic leaps after opening up its economy only in the 1990s, years after China. He took out his iPhone to illustrate the widely publicized recent success: about 15 percent iPhone manufacturing now takes place in Indiaa figure that could continue to rise rapidly, he said.

However, more broadly, India still struggles to attract foreign investment, despite improvements in infrastructure and some simplification of regulations. Manufacturing is not growing fast enough to bring India the jobs it desperately needs.

“Where India is leaving a lot of progress, jobs and growth on the table, it is figuring out a better way to make it seamless and smooth to invest here for exports,” said Mr. Garcetti. “Because it’s still, you know, for so many components of production, one of, if not the, highest tariff economy.”

“They are not wrong when they look and say that before it was 95 percent worse,” said Mr. Garcetti. “But if that 5 percent is still twice your competition or 10 times your competition — companies are, you know, like water. They flow where gravity takes them.”