Earlier this week, Russia fired over 100 missiles at Ukraine after a humiliating retreat from Kherson last week, according to officials. The attacks caused power outages and hit at least three residential buildings in Kyiv.

On Tuesday, a missile crossed into NATO member Poland. According to the Deseret News, an intelligence official from the U.S. initially reported the missile as a Russian attack that crossed into Poland during a raid on Ukraine’s energy facilities. However, further assessments from NATO and Poland suspect Ukraine launched the missile.

Zelenskyy insists the Poland missile was not from Ukraine. Here’s what investigators have found

A missile hit Poland on Tuesday, killing two civilians. Blame has been placed on Russia by U.S. intelligence and on Ukraine by NATO and Poland. Now the question is, who did the rocket belong to?

Ukrainian President Volodymyr Zelenskyy has continued to assert that the missile didn’t come from Ukraine. “I have no doubt that it was not our missile,” Zelenskyy said, according to The New York Times.

Russian authorities have spoken out against Zelenskyy and say that this was an attempt to escalate the conflict.

The investigation of the strike in Poland is ongoing. U.S. Secretary of State Antony Blinken said on Thursday that the U.S. hasn’t found anything that contradicts Poland and NATO’s assessment that Ukraine is to blame for the blast.

The Guardian reports that Blinken said that Russia is still ultimately responsible for the incident. “Whatever its final conclusion, we already know the party ultimately responsible for this tragic accident, Russia,” Blinken said.

It is believed by NATO that the Ukraine missile strike was likely to be a defense against Russian strikes, per The Washington Post.

Russia continues to issue strikes against Ukraine

Russian shelling hit Ukraine on Thursday morning, while attacks have been reported across the country, CNBC reports. This wave of attacks is reportedly the biggest strike in more than a month.

CNN reports that Russian strikes have targeted energy facilities across Ukraine, leaving millions without power again.