On a rainy night in June, President Biden toasted President Narendra Modi of India during a state dinner at the White House, celebrating “two great friends, and two great powers” — a gesture of flattery for a leader he has enlisted to help the United States check China’s ambition and counter Russia’s aggression.
According to the White House, the president had no idea that a significant test to that relationship was unfolding, even during the state visit.
On June 22, as Mr. Biden pulled out all of the diplomatic stops to bring Mr. Modi closer, a senior official in the Indian government was offering the “go ahead” approving the murder-for-hire plot surrounding a Sikh American on U.S. soil, according to a Justice Department indictment filed in a federal court in New York Wednesday.
There was one flaw: The hit man turned out to be an undercover law enforcement officer, prosecutors said, and the plot was foiled. The suspect, an Indian national accused of trying to arrange the killing, was arrested in the Czech Republic on June 30, eight days after the state dinner.
The United States has no information that Mr. Modi was aware of the alleged plot, according to several U.S. officials. But the audacious scheme illustrates how complicated it can be for American presidents to balance their relationships with deeply imperfect allies, while also trying to preserve a commitment to the values of human rights and democracy.
Mr. Biden’s advisers and analysts say the relationship between the two countries remains as strong as it was on that evening in June, driven by Mr. Modi’s desire to assert his country as an economic superpower and Mr. Biden’s need for a powerful ally to serve as a counterbalance to Russia and China.
“India remains a strategic partner, and we’re going to continue to work to improve and strengthen that strategic partnership with India,” John F. Kirby, a spokesman for the National Security Council, told reporters on Thursday. But, he added, “we’ve been clear that we want to see anybody, anybody that’s responsible for these alleged crimes, to be held properly accountable.”
After the White House was told in July about the alleged murder-for-hire plot, some officials expressed surprise, even disbelief, that India would risk upsetting the warming relations with such a brazen plan, U.S. officials said. Some White House advisers expressed private regret that the state-visit invitation was extended in the first place, officials said.
Publicly, though, the episode has not caused a rupture. As Mr. Biden has worked to build a network of global alliances to counter adversaries, he has at times soft-pedaled differences and raised difficult issues in private rather than putting them on public display.
His advisers say he has done that by meeting with Mr. Modi at the Group of 20 in India in September, where he emphasized how serious the United States took the allegations, according to a senior U.S. official who was not authorized to detail the conversation.
Mr. Biden has employed a “keep-them-close” strategy with Israel, as well. His aides say the president’s public solidarity with Prime Minister Benjamin Netanyahu after the Oct. 7 attacks by Hamas has allowed him to use his influence privately on issues such as humanitarian aid.
Whether the strategy will work in the long term remains to be seen. But it is clearly Mr. Biden’s preference to hold friends closer, using positive reinforcement to try to change their policies.
“These allegations in this investigation, we take it very seriously,” Mr. Kirby said on Thursday. “And we’re glad to see that the Indians are, too.”
Attorney General Merrick B. Garland has often said he does not discuss ongoing investigations with White House officials, usually in response to questions about the Justice Department’s indictments of his son, Hunter Biden, and of former President Donald J. Trump.
But criminal probes of foreign nationals that have foreign policy implications can be another matter. Department officials routinely flag important investigations to the State Department, members of the intelligence community and even the National Security Council if they could affect international relations, according to current and former law enforcement officials. Then high-profile gatekeepers, including the national security adviser and the chief of staff, decide when and whether to brief the president.
The federal prosecution of the Indian man charged, Nikhil Gupta, began as a relatively routine investigation into drug trafficking, federal law enforcement officials said. In late July, about a month after Mr. Gupta’s arrest, the president’s advisers were briefed when it became clear that the case was not only a criminal investigation but involved the Indian government, according to a person familiar with the investigation.
By early August, Mr. Biden had dispatched top aides to New Delhi, officials said.
In October, the Avril D. Haines, the director of national intelligence, traveled to India to lay out much of the material the government made public in Wednesday’s indictment, according to U.S. officials. In the days following that, Indian officials assured Washington that they would begin their own investigation.
In recent months, as a parade of American officials — including Ms. Haines, William J. Burns, the C.I.A. director, Secretary of State Antony J. Blinken and Mr. Biden himself — have confronted India with a message that Washington would not tolerate assassinations across North America.
U.S. officials say they do not know whether senior levels of the Indian government were involved in the alleged plot. Intelligence agencies are continuing to try and gather information, but U.S. officials said much will depend on the cooperation of the Indian government.
Mr. Biden has worked to stabilize relations with leaders of authoritarian regimes, most recently when he met with President Xi Jinping of China two weeks ago in San Francisco.
As a candidate, Mr. Biden promised to make Saudi Arabia a “pariah” for a host of human rights abuses and the murder and dismemberment of Jamal Khashoggi, a U.S. resident who was critical of the Saudi government in columns he wrote for The Washington Post.
In the years since, Mr. Biden has visited Saudi Arabia and shared a fist bump with Mohammed bin Salman, the country’s crown prince. He has shifted his stance in pursuit of long-shot bids to lower oil prices and broker a relationship between Israel and the Saudis.
Nirav Patel, the chief executive of the Asia Group and a deputy assistant secretary of state under President Barack Obama, said in an interview said that “there is a realpolitik orientation to how not only this administration but previous administrations have attempted to manage areas of divergence.”
Officials have made the case that the work to bring Mr. Modi into the diplomatic fold has helped U.S. officials to work with Indian counterparts as the investigation continues.
It has been a different approach than the one taken by Prime Minister Justin Trudeau of Canada, whose country is home to the largest population of Sikhs outside of India. Relations between the two countries devolved after Mr. Trudeau accused the Indian government of involvement in the June 18 killing of the Sikh separatist Hardeep Singh Nijjar in Surrey, British Columbia.
Mr. Nijjar was a vocal proponent of independence for Punjab, a northern Indian state that is home to a large number of Sikhs. So was Gurpatwant Singh Pannun, who U.S. officials say was the intended victim in the case unsealed this week.
Mr. Modi’s government has pushed for the extradition of 26 Sikh separatists, on the grounds that they could pose an extremist threat. The indictment unsealed on Wednesday says that Mr. Gupta told an associate that three other killings were planned in Canada, in addition to the plan to kill Mr. Pannun in New York.
Ed Shanahan contributed reporting.