WASHINGTON (AP) — The Biden administration is nervously watching a dispute between Canada and India, with some officials concerned it could upend the U.S. strategy toward the Indo-Pacific that is directed at blunting China’s influence there and elsewhere.

Publicly, the administration has maintained that Canadian Prime Minister Justin Trudeau’s allegations that the Indian government may have been involved in the killing of a Sikh separatist near Vancouver are a matter between the two countries.

But U.S. officials have also repeatedly urged India to cooperate in the investigation. Those calls have been ignored thus far by India, which denies the allegations.

Behind the scenes, U.S. officials say they believe Trudeau’s claims are true. And they are worried that Indian Prime Minister Narendra Modi may be adopting tactics to silence opposition figures on foreign soil akin to those used by Russia, Iran, Saudi Arabia and North Korea, all of which have faced similar accusations.

Perhaps of more concern, though, is that the Canada-India dispute could have major implications for one of the administration’s main foreign policy priorities: the Indo-Pacific strategy, which seeks to counter China’s increasing assertiveness in the region, according to numerous U.S. officials who spoke on condition of anonymity due to the extreme sensitivity of the matter.

Both Canada, a Pacific country and key NATO ally that shares with the United States the longest undefended border in the world, and India are critical to U.S.-led efforts to present a united and democratic front against growing Chinese assertiveness.

Aside from countering Russia’s war in Ukraine, the administration has been most focused on dealing with China as a competitor and the potential international threat it poses. To that end it has boosted its diplomatic efforts in the Indo-Pacific, including by creating a leaders group that brings together Australia, Japan, India and the United States. President Joe Biden has hailed the formation of the so-called Quad as a key part of that effort.

The fear — albeit a worst-case scenario envisioned by U.S. policymakers — is that the dispute will escalate in the same way that Britain’s row with Russia did over the poisoning of former Russian spy Sergei Skripal and his daughter in Salisbury, England, in 2018.

In that case, Britain accused Russia of an assassination attempt on its soil and expelled 23 Russian diplomats from the country. It also sought similar action from its NATO allies and European partners, which almost all agreed to take. For its part, the U.S. expelled 60 Russian diplomats and ordered the closure of Russia’s consulate in Seattle in solidarity with its British ally. Russia responded with reciprocal actions, including closing down the U.S. consulate in St. Petersburg.

Shortly after Trudeau made public his allegations last month and expelled a senior Indian diplomat, U.S. officials began to fret over the possibility that Canada might decide to go “full Skripal” with mass diplomatic expulsions and make requests, as the British did in 2018, of its allies to do the same.

If asked by Canada to expel a large number of Indian diplomats, these officials said, the U.S. would have little choice but to comply. That, in turn, could lead to a rupture in U.S.-Indian relations and the possibility that India might either narrow its cooperation with the Quad or drop out entirely.

At the moment, there’s relief it hasn’t escalated to that point yet — but that could still change.

“I’m not saying we’re at the danger zone yet,” said Danny Russel, a former senior diplomat in President Barack Obama’s administration, who is now vice president for international security and diplomacy at the Asia Society Policy Institute in New York. “But it is a situation I would certainly be watching.”

The allegation of Indian involvement in the murder was supported by intelligence from the “Five Eyes” grouping of Australia, Britain, Canada, New Zealand and the U.S.

Even before Canada made the accusations public, Trudeau had frosty encounters with Modi during last month’s Group of 20 meeting in New Delhi, and a few days later, Canada canceled a trade mission to India planned for the fall.

This week, India told Canada to remove 41 of its 62 diplomats in the country, ramping up the confrontation. Trudeau and other Canadian officials, including Foreign Minister Melanie Joly, have hinted that Canada won’t take reciprocal measures.

Trudeau has appeared to try to calm the diplomatic clash, saying that Canada is “not looking to provoke or escalate,” but officials said the concern in Washington persists.