Washington has accused Moscow of lying about a supposed US-funded biological weapons programme in Ukraine to create a pretext for its own possible chemical or biological attack on the country, where it is now expanding an invasion that has already killed thousands of civilians and driven millions from their homes.
Russian missiles struck airfields at Lutsk and Ivano-Frankivsk on Friday – the first time that cities close to Ukraine's western borders with European Union states have been attacked – and demolished a shoe factory in a largely residential area of the eastern city of Dnipro.
Several people were killed in the rocket strikes, as Russian forces continued to seek a route into Ukraine’s capital, Kyiv, and its second city Kharkiv, and kept up a siege of the southeastern port of Mariupol that has plunged its 400,000 people into a humanitarian crisis.
Russia called a meeting of the UN Security Council on Friday to discuss its unsubstantiated claims that Ukraine, the pro-western neighbour with which it has been in conflict since 2014, has run a network of covert biological warfare labs with US backing.
“The intent behind these lies seems clear, and is deeply troubling,” said Linda Thomas-Greenfield, the US ambassador to the UN.
“We believe Russia could use chemical or biological agents for assassinations, as part of a staged or false-flag incident, or to support tactical military operations.”
She said the Kremlin may “fabricate allegations about chemical or biological weapons to justify its own violent attacks against the Ukrainian people” and insisted “there are no Ukrainian biological weapons laboratories supported by the United States”.
Before Russian envoy to the UN Vasily Nebenzya made his allegations – claiming that Ukraine and the US sought to use birds, bats and insects to spread pathogens – the UN’s high representative for disarmament said she had seen no evidence of any such a plan.
"The United Nations is not aware of any biological weapons programmes" in Ukraine, said Izumi Nakamitsu.
US president Joe Biden warned that Russia "would pay a severe price if they used chemical weapons".
Civilian casualties
Ukraine says thousands of civilians have been killed since Russia invaded on February 24th and, according to the UN, some 2.5 million people have fled the country of 41 million and sought safety in EU states.
Ukrainian officials say more than 1,500 residents of Mariupol have died during a 12-day siege by Russian forces and intense bombardment of the industrial port, where apartment blocks, schools, a hospital and a maternity home have been shelled or bombed.
"Besieged Mariupol is now the worst humanitarian catastrophe on the planet. 1,582 dead civilians in 12 days, even buried in mass graves," Ukrainian foreign minister Dmytro Kuleba wrote on Twitter. "Unable to defeat the Ukrainian army, [Russia] bombs the unarmed, blocks humanitarian aid. We need planes to stop Russian war crimes!"
Ukraine’s western allies have not provided warplanes to Ukraine or imposed a no-fly zone over the country due to fears of a direct clash with Moscow, but they continue to broaden sanctions on Russia that are likely to plunge it into deep isolation.
Russian president Vladimir Putin claimed on Friday that the western embargo would help his country become self-sufficient, and said the Soviet Union "really lived under sanctions, [but] developed and achieved tremendous successes".
After invading Ukraine supposedly to demilitarise and “denazify” the western-backed democracy, Mr Putin said there were now “certain positive shifts” in diplomacy between the neighbours, without giving details.