Comment ASPEN, Cologne — Britain’s intelligence chief said Russia’s military campaign in Ukraine is likely to “run out of steam” in the coming weeks amid material and manpower shortages as Moscow’s invasion is set to enter its sixth month her. “They will have to be stopped somehow,” Richard Moore, the head of MI6, told the Aspen Security Forum – rare public remarks by the acting head of British intelligence. Russian forces had likely lost about 15,000 troops, he said, calling the number a “conservative estimate.” This is roughly the number of casualties suffered by the Russian military during the 10-year war in Afghanistan, Moore noted. A pause by Russian forces would “give the Ukrainians an opportunity to strike back,” Moore said Thursday. He said the morale of Ukrainian forces remains high and the army receives powerful weapons from the West. Moore urged that the arms flow continue so that Ukraine either prevails in the war or is in a stronger position to negotiate with Russia. He also praised the level of Western solidarity since the Russian invasion. “NATO has proven remarkably united in the face of this,” Moore said, noting that Sweden had abandoned 200 years of military non-alignment to seek membership in the alliance, along with Finland. Moore described the Russian invasion as an “epic failure” that failed to account for the stiff resistance the invading forces would face. “Clearly they completely misunderstood Ukrainian nationalism. They completely underestimated the degree of resistance the Russian military would face.” Russian officials also did not accurately convey to President Vladimir Putin the challenges of the invasion and the costs to Russia, Moore said. In Putin’s government “it doesn’t pay to speak truth to power”. In the run-up to the invasion and in the months since, there has been widespread speculation that Putin is ill, possibly with cancer, and has been portrayed as more eccentric and irrational. However, Moore dismissed rumors that the Russian president is ill, saying “there is no evidence that Putin is suffering from serious ill health.” His comments echoed CIA Director William J. Burns, who quipped earlier this week that “as far as we can tell, he’s quite sane.” The United States is also considering sending more advanced weapons to Ukraine, amid Kiev’s fears that Russian forces could be further entrenched if the war continues into the winter. “After the winter, when the Russians will have more time to dig, it will definitely be more difficult,” the Ukrainian president’s chief of staff, Andriy Yermak, said on Tuesday. Those weapons could include warplanes, Gen. Charles K. Brown Jr., the chief of staff of the U.S. Air Force, said Wednesday.