Russia is doubling down on its false claims that the U.S. and Ukraine are developing chemical or biological weapons for use against invading Russian forces, bringing the accusation to the United Nations Security Council on Friday.

A web of disinformation, not only from Russian state media but also Chinese propaganda outlets and even some American voices, have increasingly spread the conspiracy theory this week.

That’s prompted heightened concern among U.S. and Ukrainian officials that Russia itself may be planning to deploy chemical or biological weapons against Ukrainian targets or as part of a so-called “false flag” operation.

“This makes me really worried because we’ve been repeatedly convinced if you want to know Russia’s plans, look at what Russia accuses others of,” Ukrainian President Volodymyr Zelenskyy said in a televised address late Thursday, a sentiment the White House first shared Wednesday.

Ukraine does not have biochemical weapons laboratories. Instead, there are public health and veterinary health labs operated with U.S. support in Ukraine and several other former Soviet countries that provide technical support to a government’s health ministry and study disease, like the U.S. Centers for Disease Control and Prevention.

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U.S. support originated with the Cooperative Threat Reduction program, launched in 1991 to help secure and dismantle the remnants of the former Soviet Union’s biochemical weapons program in newly independent states, including Ukraine.

The U.S. has talked openly about the program throughout its history, working with 26 facilities in Ukraine on issues like biosafety and scientific mentorship training, according to the Bulletin of Atomic Scientists, an independent nonprofit dedicated to science and global security.

But in recent years, Russia, as well as China, has escalated accusations that these labs constitute a secret U.S. biochemical weapons program, at one point even claiming in state-run media outlets that they created the COVID-19 pandemic. In bitter irony, these labs have helped detect and stop the spread of COVID-19, according to public health officials.

Those false claims have skyrocketed this week, with Russian now bringing them to one of the world’s brightest spotlights — the U.N. Security Council. Russia’s mission in New York called for an emergency meeting Friday, 24 hours after its defense ministry falsely claimed it uncovered “U.S. secret military biological projects in Ukraine,” per state-run media.

“We’re not going to let Russia get away with gaslighting the world or using the U.N. Security Council as a venue for promoting their disinformation,” Olivia Dalton, the spokesperson for the U.S. mission to the U.N., told ABC News Thursday.

It’s unclear if the U.S. will try to stop the meeting, currently scheduled for 10 a.m. ET. Procedural matters, like holding a meeting, require nine of the chamber’s 15 envoys to vote in favor, and no country can veto a meeting being held.

While the false claims have escalated this week, Russian Defense Minister Sergei Shoigu ranted back in December that Ukraine, with U.S. mercenary help, was preparing a chemical weapons attack.

In 2018, Russia also made similar accusations against Georgia, the small former Soviet state that the Kremlin invaded a decade earlier as its government, like Ukraine’s, sought NATO membership. Russian forces still occupy two regions of the country, recognizing them as independent states — just as it did last month in eastern Ukraine before launching its invasion.

“The Russian allegations appear to be part of a disinformation campaign that has grown in response to scrutiny of Moscow for using and enabling the use of chemical weapons,” the Bulletin of Atomic Scientists reported in 2018 when Russia’s claims about Georgia were proven false.

The Kremlin record of “using and enabling the use of chemical weapons” runs deep, according to the Bulletin of Atomic Scientists, especially against individuals deemed enemies.

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No one is higher on that list right now than Alexey Navalny. The opposition leader and anti-corruption activist was poisoned in August 2020 with the nerve agent Novichok by agents from the FSB, Russia’s principal security agency. He was flown to Germany and recovered before returning in January 2021 to Moscow, where he was almost immediately arrested.

Another notable example before Navalny were the Skripals. Sergei Skripal, a former Russian officer who was a double agent for the United Kingdom, was also poisoned with Novichok in March 2018 in Salisbury, England. His daughter Yulia and a police officer were also hospitalized by the attack, but all three recovered.

In contrast, Ukraine has been in full compliance with the chemical and biological weapons conventions since signing them in 1972 and 1993, respectively, according to the State Department.

Asked about Ukraine’s biomedical facilities, CIA Director Bill Burns told the Senate Thursday, “In any public health system around the world, there’s going to be work done in the interests of wider public health, to ensure that we have a grip on issues like that. But that’s in no way threatening. That’s not something that can be weaponized in the way that the Russians have clearly demonstrated — by their own actions against their citizens and people outside their country — their willingness to use.”

It’s unclear whether U.S. intelligence has any evidence that Russian forces are preparing for a chemical or biological attack. The White House, State Department and Pentagon publicly pointed only to “Moscow’s track record” and “increasingly concerning rhetoric,” in the words of State Department spokesperson Ned Price.

But a senior Pentagon official told reporters, “We have picked up indications that the Russians could be making these claims — these false claims — about us and Ukrainian work in bio defense as a way of creating a pretext of their own, to perhaps use these kinds of agents in an attack.”

Pressed on what “indications” they were referring to, they added, “I have to leave it with you with indications, and [I’m] not going to be at liberty to go in more detail than that today.”

For those in Ukraine, where Russian forces have shown there’s little they won’t do to subjugate the country, the fear is real.

“The manic obsession with which various Russian officials fantasize about non-existent biological or chemical weapons or hazards in Ukraine is deeply troubling and may actually point at Russia preparing another horrific false flag operation. This tweet is for the record,” Ukrainian Foreign Ministry Dmytro Kuleba tweeted Thursday.

ABC News’ Luis Martinez contributed to this report from the Pentagon.