Poland called an emergency meeting of national security officials on Tuesday after Polish media reported that projectiles killed two people near the border with Ukraine on Tuesday.   

  Polish officials have confirmed the death of two people after an explosion in the Hrubieszów region of eastern Poland.  Government spokesman Piotr Muller said teams of experts were clarifying the situation and would work through the night to sort out the details of what he called a “serious” situation.   

  He added that Poland, which is in contact with NATO partners and US counterparts, is increasing the combat readiness of some units in the country.   

  It remains unclear where the missiles came from, but they landed on the NATO member’s territory around the same time as Russia launched its biggest wave of missile attacks on Ukrainian cities in more than a month.   

  At the scene of the explosion, Polish media showed an image of a deep impact and overturned farm vehicle, near the town of Przewodow, about four miles west of the Ukrainian border.   

  A local resident told CNN they heard a terrifying “scream” as the missile flew over the town.  A superintendent at a local school said the force of the explosion shook classroom windows about 200 meters from the school gates.   

  Polish Prime Minister Mateusz Morawiecki convened the Cabinet Committee on National Security and Defense Affairs, a government spokesman said, as reports of the missiles were published on Tuesday evening local time.   

  With little publicly known about the origin of the missiles, the incident has raised speculation that it could represent accidental transmission from Russia’s war in Ukraine.  Ukrainian President Volodymyr Zelensky has already blamed Russia, describing the deadly explosion as a “significant escalation” – a claim that Polish authorities have not confirmed.   

  Russia’s defense ministry denied targeting the border and called the Polish media reports “a deliberate provocation to escalate the situation,” according to a brief statement late Tuesday.   

  “The statements of the Polish media and officials about the alleged fall of ‘Russian’ missiles in the area of ​​the Przewodow settlement are a deliberate provocation to escalate the situation,” he said, adding that “there were no strikes.  on targets near the Ukrainian-Polish state border”.   

  He added that photos of the wreckage published by Polish media “from the scene in the village of Przewodow have nothing to do with Russian weapons.”   

  NATO Secretary General Jens Stoltenberg said on Tuesday that it was “important that all the facts be established” after speaking with Polish President Andrzej Duda about the explosion.   

  “My condolences for the loss of life.  NATO is monitoring the situation and the Allies are consulting closely.  It is important that all facts are documented,” Stoltenberg said in a tweet.   

  NATO allies responded with concern to the reports.  Some were cautious in their statements, neither speculating nor confirming the origin of the missile.   

  US President Joe Biden, according to the White House, “has been briefed on the reports outside Poland and will speak with Polish President Andrzej Duda shortly.”   

  A senior White House official says they have no confirmation of a rocket or missile attack in Poland, but that US officials are currently working to try to figure out exactly what happened.   

  State Department principal deputy spokesman Vedant Patel reiterated that the US could not confirm reports of missiles striking Polish soil, killing two.   

  “We have seen these reports out of Poland and are working with the Polish government and our NATO partners to gather more information,” Patel told a news conference.  “We cannot confirm the reports or any of the details at this time”   

  French President Emmanuel Macron called for talks at Wednesday’s G20 summit, which Biden is attending, following reports of the incident in Poland, an Elysee Palace spokesman said on Tuesday.   

  A French defense source told CNN that France is “extremely cautious” and that officials will not comment until they can “analyze all available information.”   

  A UK Foreign Office spokesman said they were “investigating these reports and liaising closely with Allies”.   

  The Baltic NATO states were more strident in their statements, underlining their readiness to defend NATO territory.   

  Estonia called the news “most disturbing,” according to a Twitter post by Estonia’s Ministry of Foreign Affairs.   

  “Estonia is ready to defend every centimeter of NATO territory,” he added.   

  Lithuanian President Gitanas Nauseda said he was concerned by the news and that “Lithuania stands in strong solidarity with Poland”.   

  “Every inch of NATO territory must be defended!”  he added on social media.   

  Latvian Defense Minister Artis Pabriks blamed Russia, although it has not been confirmed by Polish authorities that Russian missiles landed on Polish soil.   

  “Condolences to our Polish brothers in arms.  The criminal Russian regime launched missiles targeting not only Ukrainian civilians but also landed on NATO territory in Poland.  Latvia fully stands with Polish friends and condemns this crime,” Pabriks wrote.   

  The North Atlantic Treaty Organization is a group of 30 North American and European nations.  According to NATO, its purpose “is to guarantee the freedom and security of its members by civil and military means”.   

  The alliance was created in 1949 in response to the start of the Cold War.  Its original purpose was to protect the West from the threat posed by the Soviet Union.  Since the end of the Cold War, many former Soviet nations have joined NATO, much to Putin’s chagrin.   

  The best-known aspect of the alliance is Article 5 of the treaty, which, if invoked, means “an attack against one Ally shall be regarded as an attack against all Allies.”   

  Article 5 has been invoked only once, in response to the September 11, 2001, terrorist attacks on the United States.   

  However, the alliance can take collective defense measures without invoking Article 5 – and has done so in light of the Russian attack on Ukraine.   

  The State Department’s Patel said repeatedly on Tuesday that he would not discuss hypotheticals when asked about NATO Articles 4 and 5, but said intent “is something that would be important” in determining a response.   

  “As I said, we will determine what happened and determine the appropriate next steps, but as I said, this happened just in the past hour and so we continue to take the important time to figure out the exact facts,” he said.   

  Russian President Vladimir Putin has long complained that NATO has, over time, expanded its borders by admitting Eastern European countries that were once part of the Soviet Union – meaning that Russia now shares a land border with largest military alliance in the world, thereby reducing its geopolitical power in what was once Moscow’s sphere of influence.   

  As recently as February, he was demanding that NATO be reduced to its 1997 borders before the Baltic states of Latvia, Lithuania and Estonia, the latter two of which border Russia, join the alliance.