Russia May Use Chemical Weapons in Ukraine, White House WarnsWASHINGTON — The Biden administration publicly warned Wednesday that Russia might seek to use chemical or biological weapons in Ukraine as the White House rejected Russian claims of illegal chemical weapons development in the country it has invaded. This week, Russian Foreign Ministry spokesperson Maria Zakharova — without evidence — accused Ukraine of running chemical and biological weapons labs with U.S. support. White House press secretary Jen Psaki called Russia's claim "preposterous" and said it could be part of an attempt by Russia to lay the groundwork for its own use of such weapons of mass destruction against Ukraine. "This is all an obvious ploy by Russia to try to justify its further premeditated, unprovoked, and unjustified attack on Ukraine," Psaki tweeted Wednesday. "Now that Russia has made these false claims and China has seemingly endorsed this propaganda, we should all be on the lookout for Russia to possibly use chemical or biological weapons in Ukraine or to create a false flag operation using them." The U.S. for months has warned about Russian "false flag" operations to create a pretext for the invasion. Wednesday's warning suggested Russia might seek to create a pretense for further escalating the 2-week-old conflict that has seen the Russian offensive slowed by stronger-than-expected Ukrainian defenders but not stopped. Dmitry Chumakov, a Russian deputy U.N. ambassador, repeated the accusation Wednesday, urging Western media to cover "the news about secret biological laboratories in Ukraine." Pentagon press secretary John Kirby on Wednesday called the Russian claim "a bunch of malarkey." Chemical weapons use The international community for years has assessed that Russia has used chemical weapons before in carrying out assassination attempts against Putin enemies such as Alexey Navalny and former spy Sergei Skripal. Russia also supports the Assad government in Syria, which has used chemical weapons against its people in a decadelong civil war. Asked by a Russian journalist about the claims, United Nations spokesperson Stephane Dujarric said, "At this point have no information to confirm these reports or these allegations about these kinds of labs." "Our colleagues at the World Health Organization, who have been working with the Ukrainian government, said they are unaware of any activity on the part of the Ukrainian government which is inconsistent with its international treaty obligations, including on chemical weapons or biological weapons," Dujarric added. Russia has a long history of spreading disinformation about U.S. biological weapons research. In the 1980s, Russian intelligence spread the conspiracy theory that the U.S. created HIV, the virus that causes AIDS, in a lab. More recently, Russian state media have spread theories about dangerous research at labs in Ukraine and Georgia. The conspiracy theory about U.S.-run labs in Ukraine has been picked up by Chinese state-controlled media and is now circulating in online message boards popular with COVID-19 conspiracy theorists and far-right groups in the U.S. Filippa Lentzos, a senior lecturer in science and international security at King's College London, said there were no "U.S. labs" in Ukraine. Instead, she said in an email, there are labs in the country that have received money through a U.S. Defense Department threat reduction program. "These are public and animal health facilities that are owned and operated by Ukraine," she said.