The biggest swap of prisoners of war in the Ukraine conflict has come alongside an apparent shift in Russia's focus as it launches its biggest missile bombardment in months of Ukrainian defence factories.

Russia's massive increase in its aerial attacks – firing more than 500 missiles and drones in the past week, killing 39 civilians – appears designed to expose new cracks in Ukraine's war for survival.

Moscow also appears to have changed tactics by concentrating on Ukraine’s defence manufacturing sites rather than its previous winter campaign against the country's energy infrastructure.

The release of 230 Ukrainian prisoners and 248 Russians in a deal brokered by the UAE suggested a possibility for diplomacy in the conflict that has lasted almost two years.

If Moscow is probing for direction as the two-year anniversary of the conflict approaches, this week provided evidence of the carrot and stick in its approach.

Ukraine’s upgraded air defence system has been under significant pressure and was initially unable to defeat the wave of 156 projectiles but in subsequent attacks it has held firm.

Much now depends on the West supplying Ukraine with anti-missile weapons and Russia’s ability to manufacture enough ballistic and cruise missiles while also relying on North Korea and Iran.

PoW diplomacy

There had been hopes on Wednesday that the first prisoner swap since August could open a tentative path to de-escalating the war.

The UAE's Ministry of Foreign Affairs said the move had come about due to the “strong, friendly relations” between the Emirates and both Russia and Ukraine, “which were supported by sustained calls at the highest levels”.

Some of the Ukrainian prisoners had been held for almost two years after being taken captive from Snake Island on the Black Sea and in the siege of Mariupol.

Intelligence analysts have suggested the exchange at least indicates both sides are willing to talk but was still unlikely to lead to peace negotiations.

“While the PoW [prisoner of war] exchange is notable and underscores that both sides are willing to engage in low-level negotiations, we do not assess it is an indicator that peace talks are likely in the coming months,” said Alex Lord, a senior analyst at Sibylline intelligence company.

Massive barrage

The prisoner negotiations occurred during Russia’s expected blitz of Ukraine after hoarding its missile stockpile for several months.

On December 29, Russia launched its biggest strike package yet, with 36 Iranian-made Shahed suicide drones and an unprecedented 120 missiles.

An estimated 41 weapons got through Ukraine’s defences, killing 39 people and striking military and industrial hubs in Kyiv, Kharkiv, Lviv, Odesa and Zaporizhzhia.

A security assessment by Sibylline, passed on to The National, said Ukraine's air defences had “failed to intercept any ballistic missiles”, including the Kinzhal hypersonic weapons.

This indicated Russia had “increased the lethality of its swarming attacks” with the objective of undermining Ukraine’s “military self-sufficiency”.

Russia launched further mass assaults but Ukraine’s defences managed to intercept nearly all the incoming projectiles.

“The Ukrainians are rapidly learning how to deal with these attacks,” said Mr Lord. “The Ukrainian air defence network has improved remarkably compared to this time last year, especially with the provision of western-supplied Patriot missiles.”

Ballistic Iran

While Russia’s defence manufacturers can now produce an estimated 100 cruise and ballistic missiles a month, it will need imports from abroad to continue the high tempo of attack.

Moscow is intensifying its purchase of Iranian ballistic weapons and US officials have said it could also obtain numerous short-range missiles from Tehran this spring.

Meanwhile, North Korea is said to be supplying a significant quantity of missiles on top of its one million rounds of 155mm artillery ammunition, reportedly in return for Russian fighters and tanks.

Western support

If Russia can keep up the pace of attacks, it will put significant pressure on Ukraine’s defences, potentially exhausting its stockpiles.

But Europe, led by Germany and Britain, is now committing to supplying additional air defence systems, although there are “serious questions around the longevity of the West's support to Ukraine”, said Mr Lord.

Ukraine expert Orysia Lutsevych said Moscow was attempting to prove the West does not have the resources to continue fighting and would force Ukraine “to concede to Russian demands”.

“If western assistance decreases, the Russians will take more territory,” the Chatham House think tank expert warned. “They have more material and people but that's not going to break the will of Ukraine to continue defending its territory.”

Mr Lord added current western sanctions had not “significantly curtailed Russia's ability to ramp up its own military production”, so closing loopholes would be a top priority this year.

Punchbag

But boosting air defence would only create a “punchbag” for Russia and instead the West should dissuade the attacks by other means, said Keir Giles, a Russia military expert at Chatham House.

“The West should think how it can influence Russia's incentives to carry on these attacks but this discussion has been completely invisible,” he said.

“It is possible to explain to Russia that there will be negative impacts, for instance the seizure of Russian financial assets overseas, which is an obvious connection and that ought to be made public.”

He suggested the billions of Russian Central Bank assets frozen in 2022 should be used to pay for the damage the Russian state has done. That threat might make Moscow reconsider strikes on cities.

Minus 14°C

With temperatures dropping to minus 14°C in Kyiv, partly from the fallout from Europe’s Storm Henk, the Russians had chosen January, the coldest month, to attack, suggested Dr Kaushal.

But he said Ukraine’s air defences have become much more robust, particularly with the US provision of the IBCS (Integrated Battle Command System) operation centre, which gives a clear battlefield picture prioritising threats.

This allows Ukraine to shepherd its Patriot missiles using other defences to shoot down low-cost threats such as Shahed drones.

Iron will

Russia’s “pummelling” of Ukraine last winter did not “put a dent in Ukraine’s resilience to continue fighting”, said Mr Giles.

“For Ukraine, there's nowhere else to go. Surrender is not an option, because they have seen what happens to those individuals or those parts of the country subjected to daily terror by Russia. So they will fight on.”

Ms Lutsevych, who is Ukrainian-born, said her compatriots' morale remained undiminished despite the attacks.

“Although Ukraine is wounded and bitter, there's still determination to fight on because there's no alternative.”

From a military perspective, mass civilian bombardment “does not win wars”, said Dr Sidarth Kaushal, of the Rusi think tank.

But the emerging Russian tactic suggested it was preparing for a long, attritional war by degrading Ukraine’s military industrial base.

“I don't think it will be strategically decisive but it will impose significant military dilemmas on Ukraine,” said Dr Kaushal.