Russia’s invasion of Ukraine has encountered stronger resistance than expected and logistical problems have also slowed its advance, according to defence officials and military experts. As the offensive entered its sixth day on Tuesday, experts said it could be taking longer than Moscow anticipated. Britain’s defence ministry said in an intelligence update on Tuesday that Russian troops had made little progress on their push into Kyiv because of logistical difficulties. It also said Russia had failed to gain control of the airspace over Ukraine, prompting it to shift to night operations to reduce losses. It came after the Pentagon’s assessment on Monday that Russia had failed to achieve air superiority over Ukraine. There had been about 380 ballistic and cruise missile launches against Ukraine, the Pentagon said. Russia has declared “complete” control of the Ukrainian airspace, and claimed its air force destroyed about 20 more air defence system targets on Monday. Fu Qianshao, a Chinese military aviation expert and former PLA Air Force member, said Russia had destroyed some Ukrainian military targets but had failed to capture any major cities. “The Russian military has taken the initiative in the sky, but it does not have complete control in the air as the Ukrainian drones can still hit Russian targets,” Fu said. He also noted there were supply issues. “It appears that Russia might have anticipated the war being over in a few days, so they’re not adequately prepared with supplies like fuel, ammunition and food.” Fu said some Russian combat vehicles had been abandoned when they had ran out of fuel, while vehicles carrying emergency supplies had been targeted by the Ukrainian military. He added that it remained unclear whether Russia planned to enter the capital. Ukrainian forces have maintained their control over Kyiv, but a 60km convoy of Russian tanks and other vehicles are advancing on the city. Russia “planned their logistics on a blitzkrieg”, James Townsend, an adjunct senior fellow with the Centre for a New American Security’s transatlantic security programme, told USA Today. “When they started getting bogged down, they started running into logistics problems,” Townsend was quoted as saying. “They’ve got a long logistics tail. Fuel has been a bit of a big deal and that makes them targets for Ukrainian soldiers going in there with anti-tank weapons.” Retired General Peter Chiarelli, a former US Army vice chief of staff, said a prolonged conflict was likely to hit morale among Russian troops. Urban combat in Kyiv – against a motivated and well-armed population – could lead to many deaths and injuries among Russian troops, Chiarelli told USA Today. “There is nothing that will impact the morale of the force more than taking casualties and not seeing those casualties taken care of,” he said. Ill, ‘unhinged’, or calculating? Putin keeps everyone guessing Shanghai-based defence analyst Ni Lexiong said Ukraine was using portable Javelin anti-tank missiles, while lightweight, shoulder-fired Stinger missiles were being used against Russian aircraft. He said Ukraine’s resistance – with political support and arms from the US and Europe – had been underestimated by Moscow.