The US is providing Ukraine with supplies to respond to a possible chemical attack by Russia, the White House said on Friday, adding fuel to speculations about the possibility of the use of chemical weapons in the war-torn eastern European country.

“In an effort to assist our Ukrainian partners, the US government is providing the government of Ukraine life-saving equipment and supplies that could be deployed in the event of Russian use of a chemical and biological weapon,” White House Press Secretary Jen Psaki told reporters on Friday.

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The 43-year-old also declined to comment on whether the US would support Ukrainian attacks on Russia, after Moscow accused Kyiv of attacking a fuel depot in the southern Russian city of Belgorod.

“On April 1, at about 5:00 a.m. Moscow time, two Ukrainian Mi-24 helicopters entered the airspace of the Russian Federation at extremely low altitude. Ukrainian helicopters launched a missile attack on a civilian oil storage facility located on the outskirts of Belgorod. As a result of the missile hit, individual tanks were damaged and caught fire,” Russian defence ministry spokesperson Major General Igor Konashenkov said on Friday.

While Ukraine has declined to comment on the matter, open source intelligence (OSINT) investigators on social media have claimed, providing evidence, that the alleged attack was indeed carried out by Ukrainian Mi-24 helicopters using S-8 missiles.

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Asked about whether the US would support such Ukrainian attacks on Russian soil in the future, Psaki said, “I’m not going to get into a future hypothetical. What I would just reiterate again is that this is a war of aggression by the Russian leadership, by President Putin.”

The alleged attack on Belgorod has cast an air of uncertainty on peace talks between Russia and Ukraine, which resumed on April 1, and if confirmed, could seriously jeopardize efforts to negotiate a ceasefire in the eastern European country, where fighting has been going on for over a month now.