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Nato agrees with Poland's early assessment of Wednesday's missile strike - in that it most likely came from Ukrainian air defence.
Speaking to the BBC, secretary general Jens Stoltenberg said "accidents happen" in war but still put the onus on Russia. He said Russia bears the "ultimate responsibility" saying "it would not have happened if Russia hadn't waged a brutal war of aggression against Ukraine".
He emphasised the need for these type of mistakes not to "spiral out of control", adding that there are lines of communication between the US and Russia, and between Nato and Russia.