With the war now in its ninth month, US officials said there has been “a reduced tempo” to the fighting between Russia and Ukraine.
But Avril Haines, director of US Intelligence, said she expects Vladimir Putin’s forces will now “resupply” ahead of a possible counteroffensive in the spring.
“We’re seeing a kind of a reduced tempo already of the conflict and we expect that’s likely to be what we see in the coming months,” she told the annual Reagan National Defense Forum in California.
“We actually have a fair amount of scepticism as to whether or not the Russians will be in fact prepared to do that. I think more optimistically for the Ukrainians in that timeframe.”
Asked about the effects of recent Russian attacks on Ukraine’s power grid and other civilian infrastructure, Ms Haines said Moscow’s aim was partly to undermine the will of Ukrainians to resist, adding: "I think we’re not seeing any evidence of that being undermined right now at this point."
She said Russia was also looking to affect Ukraine’s capacity to pursue conflict and added that Kyiv’s economy had been suffering very badly.
Ms Haines added: "It can over time, obviously, have an impact. How much of an impact will be dependent on how much they go after, what they’re capable of doing, the resilience of that critical infrastructure, our capacity to help them defend it.
"Ukraine’s economy is suffering very badly. It’s been devastating, and obviously taking down the grid will have an impact on that as well."
The US intelligence chief said she thought Mr Putin had been surprised that his military had not accomplished more.
"I do think he is becoming more informed of the challenges that the military faces in Russia.
“But it’s still not clear to us that he has a full picture at this stage of just how challenged they are ... we see shortages of ammunition, for morale, supply issues, logistics, a whole series of concerns that they’re facing,” she said.
After Russia’s stagnation has stalled in recent months, the Ministry of Defence reports that polling data from collected by an independent source, via Russia’s Federal Protective Service, has said 25 per cent of the public support the invasion.
In contrast, in April around 80 per cent of Russians supported the so-called “military operation”.