Poland has been hit by what may have been a Russian missile, marking the first explosion on NATO soil since Moscow invaded Ukraine more than eight months ago and raising fears of a dramatic escalation of the conflict. The explosion on Tuesday killed two people and prompted Poland to consider triggering Article 4 of the NATO treaty, which would trigger consultations with the rest of the alliance, a step before invoking NATO’s collective defense provisions and brings the pact to the brink of war. with nuclear-armed Russia. The Polish explosion came on the same day that Russia fired about 90 missiles into Ukraine, one of the largest barrages since the start of the war. The wave of attacks followed a speech by Ukrainian President Volodymyr Zelensky at the G20 summit in Bali, outlining his country’s terms for peace talks with Moscow. One of his conditions was the withdrawal of Russia from all Ukrainian territory. US President Joe Biden called an emergency meeting of the leaders of the Group of Seven countries and the European Union, already gathered in Bali for the G20 summit, to decide how to react. Mr. Biden also spoke with Polish President Andrzej Duda and pledged US help in investigating the cause of the explosion. Coming out of the meeting, Mr. Biden told reporters that he and other leaders “agreed to support Poland’s investigation into the explosion.” He added that preliminary investigations did not show that the missile had been fired from Russia. “We’re going to make sure we understand exactly what happened,” he said. “We will then collectively determine our next step as we investigate and move forward.” He said there was “absolute unanimity” in the room on that, though he did not outline what that next step would entail. Asked about the possibility of triggering Article 5 of the NATO treaty, which obliges NATO countries to defend each other in the event of an attack on one or more of them, he would not comment, except to say that a meeting of of ambassadors will probably take place at some point. Mr Biden also condemned Russia’s “totally unconscionable” recent strikes across Ukraine and reiterated that the US supports Ukraine “totally right now” and will “continue to do whatever it takes to give them the ability to defend themselves”. Polish Prime Minister Mateusz Morawiecki called an emergency meeting of his country’s National Security and Defense Council on Tuesday afternoon. Government spokesman Piotr Muller then said the country might request consultations under Article 4 of the NATO treaty, which states that alliance members “shall consult together whenever, in the opinion of any of them, the territorial integrity, political independence or security of any party is threatened’. Poland will also increase the readiness of some military units, Mr Mueller said. Invoking Article 4 would stop triggering Article 5, which states that “an attack against an ally shall be deemed an attack against all allies.” The Polish government said the missiles appeared to be Russian-made, but Mr Duda said it was not immediately clear that the Russian military had fired them. Some pro-war Russian bloggers claimed the missiles were actually part of Ukraine’s air defense system. Images posted online from the Przewodow region, 10 kilometers from Poland’s border with Ukraine, showed a burnt-out tractor next to a deep crater in what appeared to be farmland. Other photos appeared to show projectile fragments that bore no obvious identifying marks. Local residents watch as firefighters work after a fragment of a Russian missile fell near a residential building in central Kiev on November 15. SERGEI SUPINSKY/AFP/Getty Images Russia’s defense ministry said in a statement that it had not targeted anything near the Polish-Ukraine border on Tuesday and that the incident was “a deliberate provocation aimed at escalating the situation”. Artis Pabriks, the defense minister of Latvia, a NATO member that like Poland shares a border with Russia, tweeted that “the criminal Russian regime fired missiles targeting not only Ukrainian civilians but also landed on NATO territory in Poland. Latvia stands fully with Polish friends and condemns this crime.” In Ottawa, Defense Minister Anita Anand said she was aware of the reports but added it would be “unwise to comment at this point.” He said he was “in close contact” with Polish officials and was “monitoring the situation very closely”. Other NATO leaders expressed solidarity with Poland without directly accusing Russia of carrying out an attack. Also on Tuesday, Russian missiles hit targets across Ukraine, hitting residential buildings in Kyiv and knocking out power plants in Lviv, in the west, and Kharkiv, in the east. At least one person was killed and several others injured in Kyiv after Ukrainian air defenses shot Russian cruise missiles out of the sky, causing them to fall in a residential area on the outskirts of the capital. Flames were seen coming out of a five-story apartment building. Sirens were also wailing in the southern port of Odessa and at least one explosion was heard in the center of the city. Explosions were also reported in the cities of Dnipro and Kryvyi Rih, in the center of the country. Mykolaiv, in the south. and Zhytomyr and Rivne to the west. “Russian terrorists have carried out another planned attack on energy infrastructure facilities. The situation is critical,” Kyrylo Tymoshenko, Mr Zelensky’s deputy chief of staff, said in a statement. “The situation in the capital is extremely difficult.” Kyiv Mayor Vitali Klitschko said half the city, which had a pre-war population of nearly three million, was without electricity, leaving 80 percent of residents without power. Water and heating were also affected. Authorities in the city of Vinnytsia, in west-central Ukraine, were called to supply water after damage to a pumping station. The country’s largest mobile phone service provider warned of disruptions, while public transport was also disrupted in several cities. NetBlocks NetBlocks recorded a sharp drop in internet traffic in Ukraine after the attacks. The strikes were seen as a direct response to Mr Zelensky’s speech at the G20 summit, in which he presented a 10-point plan for peace in his country, including the resumption of Ukrainian food exports, an “everything for everyone”. a prisoner exchange, a special United Nations tribunal to investigate alleged Russian war crimes and an end to nuclear blackmail. “Please use all your power to make Russia abandon nuclear threats,” Mr Zelensky told the assembled leaders, referring to Russian President Vladimir Putin’s repeated threats to use weapons of mass destruction against Ukraine. Mr Zelensky referred to the summit as the “G19” as Mr Putin decided not to attend, sending Foreign Minister Sergei Lavrov in his place. The Ukrainian president’s speech and the new Russian attacks came days after Ukrainian troops entered Kherson, the only provincial capital captured by Moscow in the war. Russian troops were forced to stage a humiliating withdrawal from Kherson, which Mr Putin had formally annexed just six weeks earlier, declaring that the entire region was now part of the Russian Federation. On Tuesday, Russian occupation authorities were forced to withdraw from their new headquarters in the town of Nova Kahkovkha, which is now within range of Ukrainian artillery and missile systems located on the west bank of the Dnipro River, the new front line in the region. In Bali, Mr Lavrov said it was Kyiv, not Moscow, that was refusing to discuss peace terms. “We have repeatedly confirmed through our president that we do not refuse to negotiate. If anyone refuses to negotiate, it is Ukraine. The longer he continues to refuse, the harder it will be to reach an agreement.” In Kyiv, Daniel Bilak, a Canadian lawyer who advised several Ukrainian prime ministers before they took up arms to help defend the country, said the missile attacks made it clear that the Kremlin does not want peace. “The day President Zelensky unveils a tangible, credible 10-point peace plan around which to negotiate, the Russians respond by dropping 100 deadly missiles on our heads across the country,” Mr. Bilak said. “What to negotiate?”