Ukrainians revelled at a surreal display of burnt-out Russian tanks and armour laid out as war trophies in central Kyiv to mark 31 years of independence this week, but fears of fresh Russian attacks lurked behind the show of defiance.

The sense of an eerie calm before the storm grew on Tuesday as the U.S Embassy told its citizens to leave Ukraine because of fears of possible Russian missile strikes on Independence Day on Wednesday. Kyiv has warned Moscow of a powerful response if it does so.

The public holiday, which falls six months into Russia's invasion, is often marked with a military parade, but Kyiv, fearing attacks on mass rallies, has banned public events in the city this year. It is keeping its plans to mark the date under wraps.

In the run-up to the state holiday, residents were out in crowds on the central thoroughfare, posing for photos by the carcasses of Russian tanks and eating candy floss coloured in the yellow and blue of the national flag. Young men tried to hold up the tank barrels above their heads as if they were weightlifting.

They mused at the irony of the display of armour months after Chechen leader Ramzan Kadyrov who is an ally of Vladimir Putin touted plans for a Russian military parade in Kyiv - until Moscow's assault on the capital was abandoned in March.

"Putin dreamed of a parade on Khreshchatyk, well - here it is," said Pavel Pidreza, 62, a retired Ukrainian soldier who was admiring the tanks on a stroll with his wife, Vira.

As they talked of defiance and national resilience, residents also spoke plainly of their grief at six months of war that has killed thousands, displaced millions and levelled whole cities.

Swathes of Ukraine are occupied and there is deep apprehension that the looming winter could be by far the worst since 1991 with natural gas and coal shortages threatening everything from electricity supplies to heating in homes.

Among the revellers in central Kyiv on Monday was a man named Oleksandr who became lost in tears reflecting on the six months of devastation and exclaimed in a trembling voice that he was unable to speak further.

"Probably no one has done as much to unite Ukraine as Putin, said another resident, Yevhen Palamarchuk, 38. "We always had some internal tensions in the country but since 2014, and especially since February, we are united more than ever."

He said that he, like his friends, were eagerly waiting to see Ukraine regain territory in the south in a much-vaunted counteroffensive after using sophisticated Western-supplied weapons to harry and hit Russian supply lines.

"People are weary with the war, but they are optimistic. It helps that we are getting weapons from the West ... Everyone is waiting for the first major success of our military," said Palamarchuk.

ANTICIPATING RETALIATION

But the mood music has taken a sinister turn and many in Ukraine anticipate fierce retaliation from Russia in the coming days for an array of incidents and pretexts that have gone unanswered.

They point to a spate of explosions in Crimea, the Ukrainian peninsula annexed by Russia in 2014 and prized by Moscow, that Ukraine has not claimed responsibility for, while coyly hinting its forces had played a part.

A fresh element now is the violent death outside Moscow of the daughter of one of Russia's most prominent nationalist ideologues.

Darya Dugina, a journalist backing the invasion, was killed in a car bomb and Moscow blamed her death on Kyiv despite Ukrainian denials. Russian politicians are calling her a martyr, saying her death should inspire Russian forces fighting in Ukraine.

Independence Day is one of the most important public holidays in Ukraine and has taken on hallowed significance amid what Kyiv says is a Russian imperial-style war of aggression.

Moscow casts the invasion as a special operation to demilitarise a Westward-oriented Ukraine and rid it of people it describes as nationalists, a pretext the West and Kyiv have dismissed as false.

An overwhelming majority of Ukrainians voted in support of independence from the Russia-dominated Soviet Union in a referendum in August 1991.

Palamarchuk said he saw the threat from Russia as serious, but that Putin did not have many more options for escalating his attack on Ukraine except by resorting to a radical escalation with the use of nuclear weapons.

"At this point, living in Ukraine there's always the danger of being hit by a rocket. I just don't think statistically it's very likely, that soothes me a little bit," Palamarchuk said.

Russia launched its invasion on Feb. 24, rapidly capturing a chunk of southern Ukraine, advancing in the east and driving towards the capital of Kyiv, though it was repelled around the capital and withdrew.

Moscow refocused its invasion on the industrial east, but has so far only managed to capture Luhansk region and has not made any major advances in weeks, while Ukraine has talked up plans to counterattack in the south.

"We're happy that our army is proving itself to be highly skilled, and is fighting like equals with an enemy that many countries feared, especially in Europe," said Pidreza.

He urged the West to step up supplies of military aid, arguing that Ukraine was on the frontlines against Russia defending the whole of Europe.

"We think that it (the aid) is not quite enough because we are basically fighting for the Western world."