The Polish government said a Russian-made missile killed two of its citizens Tuesday near the border with Ukraine

U.S. President Joe Biden said that it was “unlikely” that it was launched from Russia. Polish leaders convened an emergency security and defense meeting and agreed to increase its military readiness.

Polish Foreign Minister Zbigniew Rau summoned the Russian ambassador and demanded an explanation for the deadly blast in Przewodów, a settlement near the southeastern town of Hrubieszów.

"There was an explosion in Przewodów, as a result of which two of our compatriots lost their lives," Prime Minister Mateusz Morawiecki said after the meeting.

Morawiecki said Poland intends to boost "the combat readiness of selected units of the Polish armed forces, with particular emphasis on airspace monitoring."

"Talk of triggering Article 4 of the NATO charter, under which Poland would be able to summon other member states for crash talks if it feels its territorial integrity or security has been threatened"

But Polish President Andrzej Duda, in an apparent bid to lower tensions, also stressed that the government is not yet sure whether Russia fired the missile.

"We have no evidence as of yet who fired that missile," Duda said. "It was a Russian-made rocket, but the investigation is ongoing.”

"We have no evidence as of yet who fired that missile," Duda said. "It was a Russian-made rocket, but the investigation is ongoing.”

Whether intentional or by mistake, the revelation raised fears that President Vladimir Putin’s war on Ukraine could spread and escalate a regional conflict into a wider war.

Early Wednesday, Biden called an “emergency” meeting of the Group of Seven and NATO leaders who were gathered in Indonesia to discuss the attack in Poland hours earlier.

“There is preliminary information that contests that,” Biden said after then meeting when asked if the missile had been fired from Russia

“It is unlikely in the lines of the trajectory that it was fired from Russia, but we’ll see.” Joe Biden added