Ukrainian President Volodymyr Zelensky on Sunday said he was "not ready" for talks with Russia unless its invading troops withdraw, as Kyiv investigated a deadly strike on its soldiers.
The sprawling frontline between the warring sides has remained mostly static for almost a year despite a much-touted Ukrainian counter-offensive, with Russian forces entrenched in southern and eastern Ukraine.
Officials from the United States and Europe -- Kyiv's key allies -- are reported to have suggested holding negotiations to end the grinding 20-month-old conflict, which Zelensky denied on Sunday.
The United States "know I am not ready to speak with the terrorists, because their word is nothing", he told NBC television, referring to Russia.
"They have to go out from our territory, only after that, the world can switch on diplomacy," Zelensky added.
The Ukrainian leader conceded the war was in a "difficult situation" and reiterated his need for more air defences to end Russia's control of the sky.
Ukraine probes 'tragedy'
A Russian missile strike killed multiple Ukrainian soldiers at what media described as an "award ceremony" this week, leading Kyiv to open a criminal investigation.
Local media said the attack, which is reported to have killed at least 20 troops, took place on Friday as a brigade gathered to receive awards in Ukraine's southern Zaporizhzhia region.
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