NATO ambassadors have met in emergency session amid fears that Russia's war in Ukraine could spread, after a projectile struck a village inside Poland near the Ukrainian border on Tuesday, killing two people. NATO Secretary General Jens Stoltenberg said there is no indication Poland blast was a deliberate attack by Russia while Stoltenberg and Polish leaders added that there is increasing evidence missile blast was caused by Ukrainian air defense Following a meeting with the alliance envoys, Stoltenberg said at a press conference on Wednesday that there were no signs the blast in Poland caused by a missile was an intentional strike by Russia. "An investigation is ongoing, and we need to await its outcome, but we have no indication that this was an assault or a deliberate attack," Stoltenberg said, adding that there is no proof that "Russia is preparing offensive military actions against NATO." "Our preliminary analysis suggests that the incident was likely caused by a Ukrainian defense missile fired to defend (its) territory against Russian cruise missile attacks." "But let me be clear, this is not Ukraine's fault," Stoltenberg added. "Russia bears ultimate responsibility as it continues its illegal assault against Ukraine." Following the incident on Tuesday, NATO "has increased its vigilance, and we are monitoring the situation on a continuous basis," he said. Polish President Andrzej Duda on Wednesday considered it "highly likely" that the missile that killed two people on the border with Ukraine was used by the Ukrainian defense. "There is no indication that this was an intentional attack on Poland," Duda told reporters. "There is a high probability that this is a missile that was simply used by Ukrainian missile defense," he continued. It is "probably an unfortunate accident, alas," he added. Prime Minister Mateusz Morawiecki stated on Wednesday that there are "many indications" that the blast that killed two on Tuesday in a Polish village near the border with Ukraine was caused by a missile launched by Kyiv forces. "Yesterday, countering Russia's massive missile attack on Ukrainian territory, Ukrainian forces fired missiles to shoot down Russian (ones)." "There are many indications that one fell on Polish territory, without any intention of either party," Morawiecki said at a press conference, according to his office. Meanwhile, the explosion that killed two people in eastern Poland is believed to be "the result of Ukrainian air defense systems, used to counter Russian missiles," Belgian Defense Minister Ludivine Dedonder said on Wednesday. "Investigations are continuing, but at present there is no indication that it was a deliberate attack," the minister added in a statement. Ukraine has accused Russia of hitting Polish territory with a missile strike. US President Joe Biden also told G7 and NATO partners that a missile blast in eastern Poland was caused by a Ukrainian air defense missile, a NATO source told Reuters on Wednesday. Russia's Defense Ministry also said on Wednesday that its strikes on Ukraine on Tuesday were no closer than 35 kilometers from the Polish border, the RIA state news agency reported. It quoted the Russian Defense Ministry as saying that experts had identified rocket fragments in images from the explosion site in Poland as elements of the Ukrainian S-300 air Defense Ministry. In another development, Ukraine sought access to the site of an explosion in eastern Poland, a senior Ukrainian defense official said on Wednesday. Oleksiy Danilov, secretary of the National Security and Defense Council of Ukraine, said Ukraine wanted a joint study of Tuesday's incident with its partners and to see the information that provided the basis for its allies' conclusions. Kyiv is "completely open to a comprehensive study of the situation," he wrote on the council's official Facebook page. Danilov also said Ukraine has evidence of a "Russian trace" in the incident and echoed Ukrainian President Volodymyr Zelensky in blaming Russia's "missile terror". Danilov provided no details of what evidence he was citing. The Kremlin on Wednesday hailed the United States' "restraint" over the missile that fell in Poland the previous day, saying Russia had "nothing to do" with the incident that sparked a flare-up of tension. "In this case, we should note the restrained and more professional reaction of the American side," Kremlin spokesman Dmitry Peskov told reporters, denouncing the "hysteria" of "senior officials of several countries who made statements without having a clear idea of what caused" the explosion in Poland. "Russia has nothing to do with the incident in Poland," he said, echoing other Russian officials who quickly denied any involvement after initial reports on Tuesday evening that a missile had fallen in Ukraine's neighboring country. — Euronews