Nato 'looking into' reports Russian rockets hit Polish territory

"Criminal Russian regime fired missiles which target not only Ukrainian civilians but also landed on Nato territory in Poland. Latvia fully stands with Polish friends and condemns this crime," he said.

An unnamed "senior US intelligence official" also told the Associated Press news agency Russian rockets had killed two Polish people.

They spoke after Poland's Radio Zet broadcaster reported that Russian missiles had claimed two casualties in Przewodów, a village in eastern Poland near the Ukraine border.

Local firefighters confirmed two people had died in a mysterious explosion the same day.

And photos of a crater and shrapnel fragments on social media fuelled speculation.

Neither the Polish government nor Nato immediately confirmed the information, but Polish prime minister Mateusz Morawiecki called an "urgent" meeting of his National Security Council shortly before Pabriks' message.

"We're still establishing facts," a Polish diplomat said.

"We are looking into these reports and closely coordinating with our ally Poland," Nato also said in a statement.

If the Przewodów strike is confirmed, it remains to be seen if Russia's actions were deliberate or accidental.

The news came the same day as Russia rained down rockets on Ukraine, including in Polish border regions.

An accidental strike was "bound to happen sooner or later," a former Nato official told EUobserver, speaking off the record.

But Russian president Vladimir Putin has a track record of deliberately escalating tensions each time that he loses ground in Ukraine. "That's what I fear [is happening]," an EU diplomat also said.

A Russian strike in Poland could see Nato invoke Article 4 "consultations" on the security emergency — as it last did when Russia invaded Ukraine in February, leading to massive Western arms shipments to Kyiv.

It could also see the Western alliance invoke its Article 5 on mutual defence for the first time since the 9/11 attacks in the US over 20 years ago.

EUobserver recently asked two experts what would happen if solitary Russian rockets struck Polish territory, for example a military airfield in Rzeszów in south-east Poland.

Luigi Binelli Mantelli, a retired naval admiral who was chief of defence staff in Italy from 2013 to 2015, said Nato might strike back at Russia in a limited capacity.

"Nato will respond showing will and determination to discourage any further action from the opponent, while avoiding any damage that can lead to escalation. For instance, avoiding collateral damage," he said.

"In other words, it's a simple prediction of losses to be inflicted possibly equal to those which occurred due to the [Russian] first strike," he added.

Jamie Shea, who teaches war studies at University of Exeter in the UK, said: "Nato would have to decide how to retaliate, choosing from a suite of [conventional] options that Nato military commanders would propose".