Poland’s National Security Council held an emergency session after two people were killed in an explosion near the Ukrainian border.
A spokesman for Poland’s Foreign Ministry, Lukas Jasina, said a Russian missile landed on its territory, killing two people.
Jasina added that Poland has summoned the Russian ambassador to ask for “detailed clarifications immediately”.
While the Polish statement did not clarify who was responsible for firing the missile, Moscow confirms it has not carried out any missile strikes near the Polish-Ukrainian border.
The Russian Defense Ministry said in a statement that reports indicating Moscow’s involvement in the incident were a “provocation” with the aim of escalation.
Military alert
If a missile is confirmed to have landed in the area, it would be the first time a missile has landed on the territory of a NATO member since the Russian invasion of Ukraine began in February.
Polish government spokesman Piotr Müller confirmed that Warsaw is raising the alert of its military units and “checking whether it is necessary to activate Article 4 of NATO”.
According to this article, “the parties shall consult each other when either of them deems a threat to the territorial integrity, political independence or security of any of the parties”.
NATO Secretary General Jens Stoltenberg said in a tweet that he had spoken to Polish President Andrzej Duda about the blast.
“I have offered my condolences on the loss of life. NATO is monitoring the situation and consulting allies carefully. It is important that all the facts are established,” he said.
A NATO official told the BBC that the military alliance was examining the reports it received and was coordinating closely with the Warsaw government.
Ukrainian President Volodymyr Zelensky has accused Russia of deliberately attacking Poland.
“This is a Russian missile attack on collective security. This is a very significant escalation. We must act,” he said.
“Terrorism is not confined to our national borders,” he said, adding that it was “only a matter of time before Russian terrorism goes further.”
Zelensky said, and his country is not a NATO member but has close ties with the alliance, that the missile attack on his country’s electricity grid was “a slap in the face to the Group of Twenty”.
“Committing the genocide of Ukrainians in response to my peace plan is a cynical slap in the face to the G20 and the world,” he wrote on Telegram.
Belgian Prime Minister Alexander De Cree said his country was on Poland’s side and that the NATO family was more united than ever.
Latvia called an emergency meeting on Wednesday.
Lithuanian President Gitanas Nauseda said every inch of NATO territory must be defended.
And in Slovakia, Defense Minister Jaroslav Nad said Russia should explain what happened.
Social media photos show damage believed to have been caused by a missile, as well as parts of it, as believed.
The BBC has been unable to verify the authenticity of the photos, but have spoken to three defense experts about what they contain.
Mark Cancian, of the CSIS Research Center, believes they could be the remains of a missile from the S-300 system. This type of missile is usually used to launch surface-to-air attacks, and Russia and Ukraine have used it throughout the war .
“It’s not clear that the missile was fired,” said J. Andres Gannon, a security expert at the US Council on Foreign Relations, who also believes it may have come from the S-300 system.
“We know that Russia uses the S-300 for ground attacks, although it is an air defense system, but Ukraine also uses it for air defense against cruise missiles,” he added.
Dr. Justin Pronk, a senior member of the Rossi Research Center, agrees that it could have come from the S300 system, but there isn’t yet enough evidence to identify it.
State news agency RIA Novosti quoted a Russian military expert as saying that Russian ballistic missiles are unable to reach Polish territory.