A US intelligence official told The AP that Russian missiles landed in Poland and killed two people.
Poland is a NATO member, which means an attack against it could trigger a response from allies.
Sen. Bob Menendez told Politico that the attack could mark an escalation of the Ukraine war.
A top Senate Democrat said that the reported missile strike in Poland could mark an escalation of the Ukraine war, in which the country's military allies are forced to act if Russia was indeed behind the attack on Tuesday.
Sen. Bob Menendez, chairman of the Senate Foreign Relations Committee, told Politico that he hoped Moscow would quickly clarify if the strike was unintentional because it could prompt a military response from Western allies given Poland's NATO membership.
"I hope that the Russians apologize quickly for the loss of life and express that it wasn't intentional. Obviously, if it was intentional, that has all kinds of consequences to it," Menendez told Politico. "It's definitely an enlargement of the conflict and of course it brings into question Article 5."
NATO operates under the principle of collective defense, which is enshrined in the alliance's founding treaty. It stipulates that an attack against one NATO country, such as Poland, is considered an attack against all members of the alliance. An accidental strike would be less likely to lead to the invocation of Article 5. The alliance's collective defense mechanism has only been invoked once, following the 9/11 terror attacks against the US.
Details surrounding the explosion in Poland on Tuesday are still emerging.
A US intelligence official told The Associated Press that Russian missiles landed in an eastern Polish village on Tuesday and killed two people. Polish media also reported the strike.
Adrienne Watson, a spokesperson for the White House National Security Council, tweeted on Tuesday that the agency "cannot confirm the reports or any of the details at this time."
Russia's defense ministry denied responsibility for the attack and said that the reports were a "deliberate provocation to escalate" the ongoing conflict in Ukraine, according to TASS, a Russian state-owned news agency.
Meanwhile, NATO Secretary General said that he spoke to Poland's president and offered his condolences. Stoltenberg said NATO is "monitoring the situation and Allies are closely consulting," adding, "Important that all facts are established."
Read the original article on Business Insider