NATO convened an emergency meeting of ambassadors in Brussels on Wednesday after a missile crashed near the Polish town of Przewodow on Tuesday, killing two people.
"We have no indication this was the result of a deliberate attack, and we have no indication that Russia is preparing offensive military attacks against NATO," the military alliance's Secretary-General Jens Stoltenberg said after the meeting.
However, Stoltenberg noted that the incident happened as Russia launched a "wave of indiscriminate missile attacks" across Ukraine on Tuesday.
"Our preliminary analysis suggests that the incident was likely caused by a Ukrainian air defense missile fired to defend Ukrainian territory against Russian cruise missile attacks," he said.
"But let me be clear, this is not Ukraine's fault. Russia bears ultimate responsibility as it continues its illegal war against Ukraine."
Polish President Andrzej Duda also said that the missile crash was most likely an "unfortunate accident" and not an "intentional attack."
Poland is one of 30 members of the NATO military alliance. Each member state has agreed to defend each other against attacks from countries outside the bloc.
The European Union has also pledged support to Poland. Russia has denied any involvement in the missile strike.
Investigations into where the missile came from are currently ongoing.
'No call for an Article 4 meeting'
If a NATO member is attacked, it can invoke Article 4 of the NATO treaty, which begins formal consultation among the 30 members on how to respond to a perceived threat.
On Wednesday, Stoltenberg played down speculation that NATO members could be drawn into a conflict.
"Allies agree on the approach — there's been no call for an Article 4 meeting," he said. "That's based on the findings, based on the analysis, and based on the results so far of the ongoing investigation."
He added: "We agreed on the importance of waiting the outcome of the investigation."
Ukraine seeks access to crash site
A senior Ukrainian defense official has asked for immediate access to the missile blast site in Poland, as well as to see the information that formed the basis for its allies' conclusions.
Oleksiy Danilov, Secretary of the National Security and Defense Council of Ukraine, said Kyiv is "completely open to a comprehensive study of the situation."
He also claimed Ukraine has evidence of a "Russian trace" in the incident but did not provide details.
Ukrainian President Volodymyr Zelenskyy echoed a similar line, in televised remarks on Wednesday.
"I have no doubt that this is not our missile," Zelensky said. "I believe that this was a Russian missile, based on our military reports."
The president pressed for Ukrainian involvement in an investigation on the attacks, stressing that Kyiv had not seen any proof that the missile was Ukrainian.
Hungary meanwhile criticized Zelenskyy's insistence on Russia's responsibility for the missile. Gergely Gulyas, chief of staff to Hungarian Prime Minister Viktor Orban, described the Ukrainian president's accusations as "wrong" and a "bad example."
"In such a situation, world leaders speak responsibly," he told reporters on Wednesday.
Moscow calls for 'measured' response
Russia's Defense Ministry said photos of the wreckage in Poland "were unequivocally identified by Russian military experts" as being from an S-300 air defense system, as opposed to one of its own missiles. It did not provide further evidence.
Speaking to reporters in Russia on Wednesday, Kremlin spokesperson Dmitry Peskov accused some countries of making "baseless claims" about the missile incident and said the US response has been more measured in comparison.
"In this instance, attention should be paid to the measured and more professional response from the American side," he said.
US President Joe Biden said he is awaiting the results of an investigation before placing blame on any country.
Where did the missile come from?
Initial reports stated the missiles had been fired from Russia, however, the claim could not be verified.
Preliminary findings from the ongoing investigation now show the rocket may have been fired as part of a Ukrainian air defense system, NATO officials said.
US officials also stated that the missile could have been fired by Ukrainian forces at an incoming Russian missile, the Associated Press reported.
However, nothing has been confirmed.
Several countries, including China and Germany, have called for calm pending investigations into the missile strike, with German Chancellor Olaf Scholz warning against drawing any "hasty" conclusion about the missile's origin.
zc, los/sms (AFP, Reuters, AP, dpa)