On Tuesday, Russia fired over 85 missiles at Ukrainian power plants, causing blackouts in several major cities along the border, as well as affecting the neighboring nation of Moldova.

A U.S. official has since confirmed via The Associated Press that two of Russia's missiles crossed into Poland, killing two people. While seemingly unintentional, Poland is a NATO country, meaning an attack on the country could trigger a global response.

While Polish government spokesman Piotr Mueller did not confirm the deaths or the strike, he said that the country's leaders, including the Prime Minister, are holding an emergency meeting due to a “crisis situation.”

Article 5 of NATO agreements, also known as collective defense, ensures that "an attack against one Ally is considered as an attack against all Allies." It was previously invoked for the first time in the organization's history after the 9/11 terrorist attacks on the United States. It remains to be seen if it will be enacted in response to Russia's actions.

The projectiles that struck Poland destroyed a grain mill in Przewodów, a village near the border of Ukraine. The shelling was the largest wave of missile strikes in nine months of war. One casualty in Ukraine has been documented at a residential building, while the cities of Kyiv, Lviv and Kharkiv are currently without power.

President Volodymyr Zelenskiy warned citizens in a video that strikes may continue, but added: "We are working, we will restore everything, we will survive."