Ukraine‘s president said on Saturday that reports that his country has started shelling regions held by Moscow-backed separatists and within the Russian border are “pure lies,” adding that his country would not respond to provocations.

President Volodymyr Zelenskiy was speaking to senior Western security officials at the annual Munich Security Conference amid reports of explosions in Russian territory to Ukraine’s east and in Ukrainian separatist territories.

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“What was shown yesterday in the temporarily occupied territories, some shells allegedly flying from our side, some flying all the way to Rostov, these are pure lies,” he said. “They are blowing up something on their side.”

He urged Western countries to put sanctions on Russia now, rather than waiting for a hypothetical Russian invasion.

Russia, which has amassed 150,000 troops along Ukraine’s eastern borders, has stated that it need a pledge from Kyiv that it will never join the NATO military alliance for its own long-term security.

Leaders of Western countries, however, who believe Russia is planning an invasion of Ukraine, warned Russia that if it invaded, it would meet grave repercussions, and warned Moscow against attempting to redraw Europe’s borders.

“National borders should not be changed by force,” US Vice President Kamala Harris said. 

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“We have prepared economic measures that will be swift, severe, and united,” she said. “We will target Russia’s financial institutions and key industries.”

Both Ukraine and NATO members have refused to rule out Kyiv joining the alliance at some point in the future, but few anticipate it to happen anytime soon.

However, Zelenskiy implored delegates not to let the hyperbole mask the hardship of regular people, citing an explosion at a daycare in the occupied east.

“Those kids aren’t heading towards NATO. They are heading to their classrooms,” he said.

Many attendees at the conference asked Russian President Vladimir Putin to de-escalate after he presided over a nuclear drill using ballistic missiles on Saturday.

“History has not yet been written: there is an exit that the Russian government can choose at any time,” said German Foreign Minister Annalena Baerbock after a meeting of Western foreign ministers.

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“Our common message to them is very clear: Don’t make this fatal mistake. Withdraw your troops … Let’s talk.”

She claimed that Western countries had agreed on tailored sanctions packages that were ready to go in a variety of situations, including if Russia used Ukraine’s actions as a justification for an invasion.

In his approach to Ukraine, German Chancellor Olaf Scholz said Putin looked to be guided by a certain sense of history, but cautioned that this route would lead to everlasting conflict.

“Putin has clearly been dabbling lately in Russian history,” Scholz cited Putin’s written essays bemoaning the fall of the Soviet Union and the end of “historical Russia,” as well as his recent meetings with the Russian leader.

Putin’s claims of a genocide in east Ukraine were likewise condemned as “ridiculous” by him.

According to the Interfax news agency, the Russian foreign ministry stated that Scholz’s remark was “unacceptable.”

Chinese Foreign Minister Wang Yi, whose country and Russia are diplomatic allies, slammed all parties in the conflict, citing a resurgent “Cold War mentality” in the conflict.

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He stated that no country, not even a superpower, should substitute its own will for international principles.

Boris Johnson, the British Prime Minister, drew a connection between Russia’s aims in Ukraine and China’s in Taiwan, suggesting that Western leaders had a responsibility to be forceful.

“If Ukraine is invaded, the shock will echo around the world. And those echoes will be heard in east Asia and will be heard in Taiwan,” he said. “People would draw the conclusion that aggression pays, and that might is right.”