US officials became aware of the alleged plot to kill Gurpatwant Singh Pannun, who is considered a terrorist by the Indian government, last spring.
The unnamed government official was mentioned in an indictment, unsealed in Manhattan federal court, that charged Nikhil Gupta, 52, an Indian national who had lived in India, with murder-for-hire and conspiracy to commit murder-for-hire.
"The defendant conspired from India to assassinate, right here in New York City, a US citizen of Indian origin who has publicly advocated for the establishment of a sovereign state for Sikhs, an ethnoreligious minority group in India," US Attorney Damian Williams said in a release announcing the charges against Mr Gupta.
Mr Gupta was arrested on June 30 by Czech authorities through a bilateral extradition treaty between the US and the Czech Republic, according to the Associated Press. It was not immediately clear when he might be brought to the United States.
Authorities said the plot was directed by an Indian government agency employee who has described himself as a "senior field officer" with responsibilities in "security management" and "intelligence", according to the indicment, seen by the AP.
He also claims to have served in India’s Central Reserve Police Force and been trained in "battle craft" and "weapons”. Mr Pannun was only identified in court papers as the "Victim."
The Indian government employee recruited Mr Gupta last May to orchestrate the assassination, the indictment said.
The White House declined to comment directly on the charges against Mr Gupta, but a senior administration official confirmed that it first became aware of the plot in late July.
"When we were made aware of the fact that the defendant in this case had credibly indicated that he was directed to arrange the murder by an individual who is assessed to be an employee of the Indian Government, we took this information very seriously and engaged in direct conversations with the Indian government at the highest levels to express our concern," White House National Security Council spokesperson Adrienne Watson said in a statement shared with AP.
The official, who spoke on the condition of anonymity, said a number of exchanges had taken place with Indian governmental counterparts prior to Mr Gupta’s detention, in which it was stressed that those responsible for the plot must be held to account.
White House national security adviser Jake Sullivan reportedly told his Indian counterpart, Ravi Sinha, that the US needed an assurance that this would not happen again and warned that another episode could permanently damage the trust established between our two countries, the official said.
The indictment stated that Mr Gupta had contacted an individual he believed to be a criminal associate to help find a hitman to carry out the killing. However, the individual happened to be a confidential source working with the DEA.
The confidential source then introduced Mr Gupta to a purported hitman, who was actually a DEA agent.
In June, the Indian government employee gave Mr Gupta the home address of Mr Pannun, his phone numbers and details about his daily conduct, including surveillance photographs, which Mr Gupta then passed along to the undercover DEA agent, the indictment said.
It said Mr Gupta directed the undercover agent to carry out the murder as soon as possible, but also warned the agent not to commit the killing around the time of anticipated engagements between high-level US and Indian officials.
The charges against Mr Gupta that implicate the Indian government official comes shortly after similar concerns were raised in Canada over the death of another Sikh activist.
In September, Canadian Prime Minister Justin Trudeau said there were “credible allegations” that the Indian government may have had links to the assassination in that country of Sikh activist Hardeep Singh Nijjar.
India rejected the accusation as “absurd” and “malicious”, but Canada expelled a top Indian diplomat and India responded with the same measure.
According to the New York indictment unsealed Wednesday, Mr Gupta told the undercover DEA agent the day after Nijjar’s murder that Nijjar "was also the target" and "we have so many targets" and he added that in light of Nijjar’s murder, there was "now no need to wait" in carrying out the New York assassination.
Canadian Foreign Minister Melanie Joly declined to comment on the US indictment but said "we stand by our own credible allegations that there was a killing of a Canadian on Canadian soil linking to Indian agents."
Ms Joly said she’s had numerous conversations US with Secretary of State Blinken about the matter as well as her Indian counterpart.