The Pentagon released on Thursday a video showing a Russian military jet intercept a US drone downed over the Black Sea two days ago, in what was the first direct encounter between the world's leading nuclear powers since the Ukraine war began. The rare Pentagon move came a day after US and Russian defense ministers and military chiefs held phone conversations over the incident that saw the MQ-9 Reaper drone crash into the sea while on a reconnaissance mission in international airspace. In the declassified, roughly 40-second video, a Russian Su-27 fighter jet comes very close to the drone and dumps what US officials say was jet fuel near it in an apparent effort to damage the American aircraft as it flew over the Black Sea. It also shows the loss of the video feed after a second pass by a Russian jet, which the Pentagon says resulted from its collision with the drone. The video ends with images of the drone's damaged propeller, which the Pentagon says resulted from the collision, making the aircraft inoperable. Russia has denied any collision and said the drone crashed after making "sharp maneuvers", having "provocatively" flown close to Russian air space near Crimea, which Moscow forcibly annexed from Ukraine in 2014. "There is a pattern of behavior recently where there is a little bit more aggressive actions being conducted by the Russians," General Mark Milley, chairman of the US Joint Chiefs of Staff said on Wednesday. Milley said it was clear that the intercept and harassment of the drone by Russian jets was intentional, but it was unclear whether the Russian pilots meant to slam their aircraft into the drone - a move that could also put them at risk. ‘Escalation’ Russian Defense Minister Sergei Shoigu told his US counterpart that US drone flights near Crimea's coast "were provocative in nature" and could lead to "an escalation ... in the Black Sea zone," a ministry statement said. Russia, the statement said, has "no interest" in escalation "but will in future react in due proportion" and the two countries should "act with a maximum of responsibility", including by having military lines of communication in a crisis. US Defense Secretary Lloyd Austin declined to offer details about his conversation with Shoigu, but said the United States would continue "to operate wherever international law allows. And it is incumbent on Russia to operate its military aircraft in a safe and professional manner". Russia has said the episode showed Washington was directly participating in the Ukraine war, something the West has taken pains to avoid. "The Americans keep saying they're not taking part in military operations. This is the latest confirmation that they are directly participating in these activities - in the war," Kremlin Security Council Secretary Nikolai Patrushev said. The United States has supported Ukraine with tens of billions of dollars in military aid but says its troops have not become directly engaged in the war, which Moscow portrays as a conflict against the combined might of the West. ‘Complex’ Bakhmut battle The drone incident came as Russia kept up a months-long drive to capture the small eastern Ukrainian city of Bakhmut, in what would be its first substantial victory in more than half a year. The Russian-installed leader of Ukraine's eastern Donetsk region said on Thursday the situation around the now-ruined city remained "complex and difficult" as Kyiv refused to withdraw its forces. "That is, we do not see that there is any premise that the enemy is going to simply withdraw units," Denis Pushilin said in an interview on state TV. Ukraine's President Volodymyr Zelenskiy said this week his military top brass had advised reinforcing Bakhmut. Kyiv had appeared last month to be preparing to pull out of the city but has since decided to defend it, saying it is exhausting Russia's attacking force there to pave the way for its own counter-attack. In its daily intelligence update on the Ukraine war, Britain's defense ministry said on Thursday Russian attempts to capture the town of Vuhledar, about 150 km (93 miles) southwest of Bakhmut, had "almost certainly slowed" after repeated, very costly failed attacks over the last three months. To the north of Bakhmut, Ukrainian troops in a bombed out village near the city of Kreminna battled to counter what they said was an attempt by Russia to undertake a giant pincer move. "The Russians try to adapt in real time," said a member of a drone unit call-signed "Zara". "This makes great problems for us, because we have to think a couple of steps ahead - how do successfully complete the mission and not let the enemy know how we did it." The war has resulted in the destruction of Ukrainian towns and cities, the deaths of tens of thousands of people and the flight of millions from their homes. It has also rocked the global economy, pushing up energy and food prices. President Vladimir Putin, meeting members of Russia's business elite on Thursday for the first time since the invasion, urged them to invest in their country to help it weather what he called the West's "sanctions war". Many of those attending the meeting are themselves under Western sanctions because of what Putin calls Russia's "special military operation" in Ukraine.