On 28 February, Oksana Markarova, the Ukrainian ambassador to the United States, stated that Russian forces used a thermobaric bomb in Okhtyrka.[24][25][26] International law does not prohibit the use of thermobaric munitions, fuel-air explosive devices, or vacuum bombs against military targets.[27][28] Their use against civilian populations may be banned by the United Nations (UN) Convention on Certain Conventional Weapons (CCW).[29] Markarova claimed that the use of thermobaric weapons is in violation of the Geneva Conventions.[30][31][32] White House Press Secretary Jen Psaki said she had seen reports but did not have confirmation that Russia had used such weapons. "If that were true, it would potentially be a war crime," she told a press briefing.[24] The attack destroyed a Ukrainian military base, killing 70 soldiers.[33]