This is Ukraine's position, they are absolutely NOT taking responsibility:
"Ukraine’s foreign minister has denied that one of their missiles was involved in the explosion, which President Volodymyr Zelensky has called an “escalation” by Russia. Russia denied involvement and said that it did not aim any missiles at the border with Poland on Tuesday.
Mr. Duda also emphasized that the events in Poland came amid a “massive, unprecedented” Russian attack on Ukraine.
“Ukraine defended itself — which is obvious and understandable — also by firing missiles whose task was to knock down Russian missiles,” he said. “Therefore, we were dealing with a very serious clash caused by the Russian side, as well as the entire conflict. Yesterday’s clash is certainly borne by the Russian side,” Duda said"
It does not sound like anyone from Nato has bothered to tell Ukraine they need to take the flak for this one.....