US Secretary of State Antony Blinken tweeted on Sunday that he spoke to Ukraine's Foreign Minister Dmytro Kuleba to 'reject Russia's false allegations that Ukraine is preparing to use a dirty bomb on its own territory'.
Earlier this week, Blinken also accused Russian President Vladimir Putin of 'doubling and tripling down' on his aggression towards the neighboring country.
'Every indication is that far from being willing to engage in meaningful diplomacy, President Putin continues to push in the opposite direction,' he said at a press conference with his French counterpart Catherine Colonna.
Earlier on Sunday, Kuleba had denounced Moscow's claims as 'absurd' and 'dangerous'.
'Russians often accuse others of what they plan themselves,' he added, before tweeting about his call with Secretary Blinken.
'We both agreed Russia's ''dirty bomb'' disinformation campaign might be aimed at creating a pretext for a false flag operation,' Kuleba wrote.
'We also discussed further practical steps to boost Ukraine's air defense. Secretary affirmed the US spares no effort to this end.'