Russia did not fire an intercontinental ballistic missile (ICBM) at Ukraine on Thursday, a U.S. official and a military officer with knowledge of the matter told NBC News, disputing a claim by Kyiv. Ukraine accused Moscow of launching the ICBM at the eastern city of Dnipro in an overnight attack, which would have marked the first recorded use of an ICBM in an active conflict and the latest escalation by the Kremlin. U.S. officials said the weapon was an experimental intermediate range ballistic missile and that Russia has a limited supply of that particular missile. Intermediate range ballistic missiles typically have a range of less than 3,500 miles. ICBMs typically have a range of more than 3,400 miles, so it’s unclear why the Kremlin would have used one against its neighbor. Such missiles can carry either nuclear and nonnuclear payloads. The Kremlin did not immediately respond to Ukraine’s accusation, with spokesperson Dmitry Peskov referring questions to the Russian Defense Ministry. The claim was disputed earlier by a Western official, who said it was a ballistic missile but not an ICBM that was fired. The Western official declined to further characterize the missile that was used, adding that its impact was still being assessed. It came as Ukrainian forces used their first long-range U.S. and British missiles to strike Russian soil after Washington and its allies lifted restrictions on Kyiv — a move that Moscow had long warned would be met with a significant response. President Vladimir Putin this week lowered the bar for his country’s use of a nuclear weapon, a move that was dismissed by Western officials as the latest instance of Russian saber rattling in the war, which has now lasted more than 1,000 days. ‘Using Ukraine as a training ground’ Speaking in a video posted on Telegram, Ukrainian President Volodymyr Zelenskyy said that “today, our crazy neighbor once again showed what he really is and how he despises dignity, freedom, and people’s lives in general… he is so afraid that he is already using new missiles.” “It is obvious that Putin is using Ukraine as a training ground,” he added, saying that that the speed and altitude of the missile that Russian forces launched suggested that it was an ICBM, but that investigations were now underway. The Ukrainian air force said earlier that the alleged ICBM was launched from the Caspian Sea region of Astrakhan in southern Russia at Dnipro, but said it had not yet received any information about whether there had been any victims. It did not specify exactly what model of missile was used. In a statement posted on Telegram, the air force said that Moscow had also attacked Dnipro with various other missiles. It said that Russian aircraft had fired an air-launched ballistic missile and seven cruise missiles, and that Ukrainian forces had shot down six cruise missiles. Serhii Lysak, the head of the regional authority, said on Telegram that two people were injured in the attack on Dnipro. Meanwhile, 15 people were injured in a separate attack on the eastern city of Kryvyi Rih, local authorities said.   A spokesperson for British Prime Minister Keir Starmer called the reports “deeply concerning” but added that intelligence services were still looking into them. “If true, clearly this would be another example of grave, reckless and escalatory behavior from Russia and only serves to strengthen our resolve,” the spokesperson said. Analysts have urged caution in interpreting Thursday’s claim by Kyiv. Using such a missile “in a conventional role does not make a lot of sense because of their relatively low accuracy and high cost. But this kind of a strike might have a value as a signal,” nuclear forces expert Pavel Podvig said. “I would urge people to keep calm, not assume automatically that “intercontinental” is something inherently and immediately dangerous. But it should be taken seriously,” Podvig, a senior researcher at the U.N. Institute for Disarmament Research, said in a post on X. Putin on Tuesday formally revised his country’s nuclear doctrine — a document detailing the conditions under which Moscow would consider using nuclear weapons — with the change justifying a nuclear strike by Russia if attacked by a nonnuclear country that is supported by a nuclear state. Ultimately, analysts say, the likelihood of the Kremlin opting to use nuclear weapons in its war with Ukraine is very slim — particularly now, when its military is advancing and its opponent is worn down. Russian forces have seized the momentum in recent months and eked out a succession of territorial gains, particularly on the eastern front lines. They have also been bolstered by thousands of North Korean leader Kim Jong Un’s troops in their quest to retake occupied land in Russia’s Kursk border region. The West relaxing restrictions on Ukraine’s use of long-range weapons may boost Kyiv but will likely do little to transform the battlefield situation, analysts said, despite the dire nature of the Kremlin’s rhetorical reaction. “At this stage in the war, the risk of Russian nuclear use is lower than before. Political and battlefield developments favor Russia, so there is little to gain by escalating the conflict to the nuclear level,” said Alexander Bollfrass, head of strategy, technology and arms control at the London-based International Institute for Strategic Studies think tank.  In addition to the unclear military benefits of deploying those weapons, there would also be diplomatic drawbacks.  “Nuclear weapons use would risk alienating China and other non-Western countries whose support or neutrality is key to maintaining the Russian war economy,” Bollfrass told NBC News in an email Wednesday. “It would also get the relationship with the incoming Trump administration off to a very dangerous start.” This article first appeared on NBCNews.com. 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